A trooper named Ukarme fights his way through a hostile jungle environment on an unnamed planet. Major Takol contacts him by radio and asks if he’s found the source of the signal yet. He tells her he’s identified the source as a male human, who wasn’t wearing a protective suit, found hiding in some caves near Sector Four-North. The man made a run for it when Ukarme approached him, so Takol orders him to resume the hunt and track the man down. Ukarme calls out to his prey and warns him he’ll start shooting if he doesn’t come out from cover by the count of three. Realising he can’t escape, the man emerges from the trees in a state of confusion. The trooper warns him not to make any sudden moves, but the man seems confused and can’t remembering who he is. Just as it finally dawns on him that his name is the Doctor, Ukarme shoots the man and he falls to the ground.

Ally has popped round to her best friend Peri’s home in order to tell her about her latest hot date, but Peri isn’t paying the slightest attention to her story and is too engrossed in the latest episode of the soap opera “Love MD”. Peri apologises and admits to being miles away, but Ally’s story was disappointing anyway since her date never showed up. It’s the fourth time that’s happened to her this year and she’s beginning to realise that not everyone is as lucky as Peri, who has a nice house, a gorgeous boyfriend and a loving son. Peri isn’t so sure about the latter as she’s still having difficulties with her boyfriend’s son Kyle. In fact, their relationship consists of Kyle slamming doors, swearing and throwing things at her. In his eyes, Peri is just a wicked stepmother and her partner Mike isn’t much help. He may be a hard-hitter at work, but when it comes to his son, he’s a pussycat. Peri is the only one who’s prepared to provide any discipline and Kyle doesn’t like it. They’ve both been summoned to see Kyle’s headmaster, but Mike has left it to her as he thinks that’s a job for the ‘mother’. She doesn’t think she’ll be long, so she invites Ally to stay here and watch television until she returns.

Queen Erimem is woken from a rest by her handmaiden Andree, who tells her First Minister Malarou has arrived. Malarou rushes in with bad news - there have been riots in many sectors with numerous casualties and massive damage done to property. Fortunately no deaths have been reported so far, but no thanks to the traitor Kharto. Erimem still finds it hard to believe this is all one man’s doing, but Malarou is sure his information is correct. Kharto may not be personally organising the rebels, but the riots have certainly been inspired by him and his seditious speeches. Erimem asks to be kept informed, then decides to call a meeting with her generals. New Cairo was built on the bones of her ancestors and made fruitful by their blood, and she refuses to stand by and watch it descend into chaos.

Peri assures the headmaster that from now on Kyle will be as good as gold. As she leaves his office, she angrily demands an explanation from Kyle for his recent behaviour and says she won’t accept his normal silent treatment. He shrugs and turns away, so she tries a different approach. This is the third time in a month that she’s been called in to see the headmaster. This is the best school in London and unless he changes his attitude, he’s going to get kicked out. She reminds him that his father works hard to send him here, and he repays it by starting a classroom brawl. Kyle asks why it’s only ever Peri that comes to the school, but she assures him that although his father is busy, that doesn’t mean he isn’t interested. She knows it must be hard for Kyle now that his dad has a new girlfriend, but she’s a part of both of their lives now so they might as well try to get along. Kyle wonders if Peri really thinks she’s going to be with Mike forever and points out that his mum used to think that too. He walks away and she runs after him…

Professor Darrius Hayton listens back to the tape recording of his experiment from the previous day, then lines the tape up to continue recording. The latest samples of bio-tissue have all demonstrated some potential, but none survived long enough under laboratory conditions to evaluate them fully, so further living samples will be required. He’s interrupted by the arrival of Major Takol who tells him High Command are expecting results and she’d like to give them something sooner rather than later. He says he’s getting close, but he needs more samples. She tells him Ukarme has been occupied tracking down a stranger outside the base so they both leave to question the new arrival.

Andree arrives with lunch for Queen Erimem. The First Minister arrives late and apologises for his lamentable tardiness. He says he’s been deep in discussion with one of his aides about Kharto, but he’s reluctant to say any more in the presence of Erimem’s handmaiden. Andree leaves and Erimem rebukes Malarou for seeing plots and treachery everywhere, pointing out that Andree has been her faithful servant for years. Erimem is about to start eating when Malarou insists that she waits until her food taster has checked it first. The Queen insists that she knows Kharto and although he may be a troublemaker, she’s sure he’s not a killer. Nevertheless, she agrees to let the food taster do his job even though she finds the idea ludicrous. She reminds Malarou that they’re living in the 25th century and she doubts that anyone’s been poisoned since the time of the Pharaohs, but just as she says that, the food taster drops his cutlery and begins choking. Seconds later, he falls to the floor, dying. Malarou orders the guards to fetch a medi-kit, but it’s too late…

Professor Hayton completes his medical scan of the Doctor and although his respiration is normal and his pulse rate is within acceptable limits, it doesn’t take him long to discover that the unconscious man has two hearts. Major Takol wonders if the man is a cybernetic, but Hayton assures her he’s humanoid and most probably an alien. This might explain how he was able to survive for so long outside without an environment suit. Takol asks him to revive the Doctor, but her request instigates another round of their old argument about the different levels of resource given to military and scientific projects. Takol reminds him that he’s not the only expert in his field and says she’s considering getting herself a new genius, but Hayton says if she’s thinking of Harvard Steel she can forget it. Not only is he out in the Zenori System on a long-term bio-energy project, his methods are questionable to say the least. He becomes angry that he’s not being allowed to conduct this research along the lines he originally suggested, but his raised voice wakes the Doctor from his unconscious state. Takol is pleased that the patient has revived without the need for any medical intervention. The Doctor politely asks if he can have a cup of tea as stun-guns always leave a dry taste in his mouth, but the Major would like him to answer some questions first. Unfortunately he can’t remember where he came from or even where he is. He seems to be having some problems with his memory, which Hayton says is hardly surprising. In fact, he’s amazed the Doctor has any memory left at all. If he’d spent any longer out there in the jungle, it would have been destroyed for good. They introduce themselves and Major Takol explains that this base was set up by the Earth Empire Space Marines. The Doctor remembers that he’s a traveller and was journeying with Peri and Erimem and he suddenly realises his two companions must still be outside in the jungle. Hayton thinks there may still be a chance to save them if they stayed inside the cave so Takol dispatches Ukarme to find them.

Erimem summons Malarou again and asks if he’s found the people responsible for the attempt on her life. He says they’ve made a number of arrests and forensic tests are currently being conducted, but the Queen is angry and wants to be told as soon as the results are in. Malarou nervously tells her that Kharto was staying at one of the houses they raided and they couldn’t ignore his presence at a base of rebel activities, so they arrested him. Erimem doesn’t think this is wise and believes it could be the spark the insurgents need, but Malarou says they couldn’t really arrest all the others and let him go. Erimem points out that if they had done, his supporters would have wondered why he’d been spared and would have suspected him of doing a deal with them, selling them out in order to save his own miserable skin. She orders him to bring Kharto to her so she can speak to him face to face. The First Minister strongly advises against this, but she insists. One thing she learned from her old friend the Doctor was never to miss an opportunity to look your opponent in the eyes. Malarou is tired of hearing the many pearls of wisdom from the Doctor, but Erimem reminds him that the Doctor is still a very good friend of hers. Malarou wonders why then did he leave her? Erimem is momentarily confused, but she convinces herself that she must have left the Doctor rather than the other way round…

Privately, Major Takol asks Hayton whether he thinks the Doctor is telling the truth. The Professor is convinced he is and says he genuinely seemed confused when he woke up. In any case, if he knew anything about this planet he wouldn’t have been out in the jungle unprotected. Takol suspects it may have been a ruse to allay their suspicions and gain entry to the base, but Hayton believes this is a product of her own twisted imagination. The Doctor would have to be a fool or a madman to take a risk like that, but Takol points out that if he really is an alien, he may have a means to survive out there. Perhaps they should cut him up to see how he ticks. The door opens and the Doctor enters cheerily. The Major notes how quickly he seems to have recovered and he agrees that he has pretty good recuperative powers for a man his age. He asks about his companions, but there’s no news yet as Ukarme is still searching for them. The Doctor is impressed by the base and asks if he could look around, so Hayton offers to give him a grand tour. He tells the Doctor the planet doesn’t have a name and is listed simply as YT45. As they move off, Takol notes how many questions the Doctor is asking and mutters to herself that curiosity killed the cat.

Erimem is becoming irritated by the way Andree is pacing up and down, but the handmaiden says she is fearful for her Queen’s safety. After the food poisoning incident, she’s convinced Kharto will kill Erimem given a chance, and although the Queen is touched by the youngster’s concern, she’s satisfied she is well guarded. Andree says she’s served Erimem all her life, ever since she could first walk, and the Queen agrees that she’s been a faithful companion…but then she starts to think about Andree’s words more carefully and realises what she’s said can’t be right - if Andree had served her since she was a child, that would mean she’s been here about 20 years. Andree confirms that Erimem has ruled New Cairo since the colony was founded over 25 years ago, but Erimem knows that’s not possible!

Professor Hayton takes the Doctor to the highlight of the tour - his laboratory. The Doctor seems to be impressed, but Hayton knows that, like the rest of the base, the room is built mainly from stock pre-fab. He’s tried to personalise it with his own clutter and the Doctor agrees that it looks a little less ’temporary’ than the other units. Hayton says this demonstrates that the military mind-set is to move and out as quickly as they can and then head for the next mission. The Doctor asks what the current mission is, but Hayton says it’s top secret. The Doctor notices a small creature in a cage that looks a bit like an oversized lemur. Hayton says it’s this planet’s answer to a primate and they call them Jekylls because they have a split personality. This one seems friendly enough during the day, but come nightfall it’s a different matter. He points out the creature’s lethal incisor teeth. It’s strong too and it could rend a man limb from limb. However, the Doctor knows the creature isn’t Hayton’s main interest on the planet. The laboratory is filled with strange plants, including some which the Doctor identifies as Methuselan poppies, Gavinci’s strangle weed (which is very nasty) and Kemsel moss. Hayton is impressed and says it’s a pleasure to meet a fellow aficionado, but the Doctor insists that he’s just an enthusiastic amateur and it’s Peri who’s really the expert.

The mention of Peri’s name makes him remember they were both examining some purple flowers like the ones here in the terrarium. Hayton identifies them as kyropites and says no one’s ever seen anything like them before. The Doctor suspects they’re the real reason the mission is here and wonders whether there’s any connection between the plants and his memory loss out in the jungle. Hayton acknowledges that the kyropites do seem to have an unpleasant effect on people and on the Jekylls too. Memory loss is part of it, but if the Doctor had been out there any longer it would have been fatal. Hayton explains that a routine survey mission landed here six months. At first everything was normal and all the data was being fast-beamed home, but then the entire survey team started died. Despite that, Major Takol decided to bring a second mission here, believing that the plants may have potential as a weapon for the military. Hayton demonstrates this by introducing Heager Worms to the kyropites kept inside a sealed container, then they watch as the flowers emit an anaesthetic gas. Hayton explains that the flowers are neurological parasites which feed telepathically from their living victims’ alpha waves. They won’t get much from the worms, but they normally feed on the local wildlife, with more spectacular results. It appears that the plants have developed some sort of symbiotic relationship with the Jekylls, and far from pacifying the primates it makes them killers - friendly by day, but deadly by night. This offers protection to the plants as the Jekylls remove any creatures that are more resistant to the anaesthetic gas from the evolutionary tree. Hayton believes this is what happened to the original survey team. Takol’s mission landed during the night cycle and they lost three of their men the same way. Anything left alive by the Jekylls is sent into a deep sleep by the gas and while the victims are dreaming, they produce plenty of alpha waves to feed the plants. Incredibly, it seems the plants actually share the dream experience. The Doctor recalls feeling a presence inside his head while he was outside, but it’s possible his history of telepathy made him less susceptible to the effects. The Doctor asks Hayton how he knows what’s going on inside the victims’ unconscious minds, and the Professor reveals that he’s able to monitor their dreams.

Deep in the jungle, Ukarme contacts the base and reports that he’s found some tracks. Takol tells him to follow them, but warns him to be careful as they’ve already lost enough people from this expedition. She doesn’t care about them personally, but nor does she want to blot her career record by adding to the numbers of deaths under her command. Ukarme notices something buried under the foliage and when he pulls the leaves and branches away, he discovers it’s a woman, alive but in deep sleep. Takol orders him to load the woman onto a drone and get her back to the base where they can both be fully decontaminated.

Hayton explains that he has a machine capable of accessing a person’s dreams. The Doctor didn’t realise the research in this field was so advanced and Hayton admits that it’s based on alien technology traded from the Dreamweavers of the Goyana System. Major Takol contacts the laboratory with the news that Ukarme has found one of the Doctor’s friends, which alarms the Doctor as he knows Peri and Erimem were together. Takol repeats that they’ve only found one - a dark-skinned girl…

First Minister Malarou brings their prisoner before Erimem. The rebel Kharto greets his Queen and humbly prostrates himself before her. Erimem dismisses the protesting Malarou, insisting she’s safe since their prisoner is handcuffed and unarmed. She also asks Andree to leave, but the handmaiden says she’d rather stay with her Queen. Erimem agrees and tells Kharto to get up, adding that his fervent loyalty is impressing no one. She tells him she’s aware that he has some ’issues’ about the way things are run around here, but he argues that it’s more than that - the future of this entire colony is in jeopardy.

Ukarme takes the Doctor and Hayton to see the woman he discovered in the jungle. The Doctor confirms that it’s Erimem and Ukarme says that when he found her she was in a deep sleep and surrounded by plants. Hayton says it would be extremely dangerous to wake her as any attempt at sudden withdrawal from the dream state can cause extensive cerebral damage. The Doctor points out that the Heager Worms made a full recovery with no ill effects, but Hayton says that’s because they were revived immediately. The dreams these plants initiate are complex neurological fantasies and they feel completely real to the victim. In some respects, they are real and the longer the victim is under, the harder it is to tear the mind away from the dream reality. Hayton explains that there are several stages. Stage one lasts only for the first few hours and there is no dreaming, just plant-induced sleep. He believes the plant uses this time to access the victim’s memories and construct a fantasy world to entrap their minds. Stage two is when the dream world has been created and the victim believes themselves to be awake inside the fantasy. Stage three is when the plant begins to physically bond with the victim, initiating a process of absorption. Stage four is death. Hayton believes Erimem is currently at stage two…

Kharto tells Erimem he would do things differently if he was ruler. He accuses her of living in the past and asks what the point is of all these reminders of living in Ancient Egypt? She says it’s important to remember where they came from, but Kharto reminds her they’re in the 25th century and the Pyramids would have been dust by now had they not been encased in plastic. Erimem argues that if they forget their past they will lose all sense of who they are, but Kharto says they’re nothing more than pale imitations of their ancestors. He asks why she came here in the first place and the question throws Erimem off balance. She can’t seem to remember, but she dismisses this as nothing more than temporary amnesia. He challenges her right to rule and says it’s no wonder the colony is on the brink of disaster. Suddenly there’s a gun shot and Kharto falls to the ground. Erimem turns furiously on Andree and demands to know why she killed him, but her handmaiden simply turns the weapon on Erimem and tells her she will be next…

In the military base, the Doctor tries to revive Erimem, despite Hayton’s warnings that it could be dangerous. He asks the Professor whether there are any stimulants they could use, but Hayton insists these aren’t just dreams, they’re complex controlled simulacrums of real life. He invites the Doctor to look at Erimem’s medical schematics which show wild variations in her heartbeat, irregular breathing patterns and massive alpha wave activity. This isn’t normal for a sleeping person and as far as Erimem will be concerned, her dreamscape is real. The Doctor asks what would happen to her if, for example, she fell off a cliff or drowned in the dream world? Hayton explains that if she dies in the dream, she’ll die here in the laboratory too.

Peri is engrossed with the next episode of the soap opera “Love MD” when Mike eventually returns home. She’d just about given up on him, but he says he was held up at the office. She jokes that he was more likely being held down by some leggy blonde, but the way she pouts when she says it makes him feel erotic. They share a kiss, then Mike asks her if everything is alright with Kyle. He’s worried that everything is becoming too much for his son and he remembers how he felt when he first started dating again after Rachel left. Kyle accepted it eventually and Mike thinks he’ll learn to accept Peri too in time. They start to cuddle again, then Mike spoils the mood slightly by asking Peri what’s for dinner.

Erimem pleads with Andree to start breathing again but, just before she dies, the handmaiden curses the Queen and says how much she despises her. Erimem turns furiously on First Minister Malarou and demands to know why he didn’t set his own weapon to stun. He explains that Andree was about to kill her so he didn’t have time to stop and think. Suddenly Kharto starts coughing and Erimem realises he’s still alive so she calls for a medic urgently. He may be an opponent, but she doesn’t consider him to be an enemy and dead, he will only be a martyr to other fanatics. If this colony is to survive, she needs him alive.

In the laboratory, Hayton reports that Erimem’s condition is stable. The Doctor is convinced there must be something they can do to help her and the Professor has an idea. It’s completely untested, but anything is better than watching Erimem die in slow stages. Hayton says he’s been experimenting on the plants, trying to extract the agent that causes these dreams, not to develop a cure but to find a means of putting someone into a similar state of unconsciousness. He can then use a Dream Scanner to harmonise the alpha waves generated in the Doctor’s hypothalamus with those of Erimem. The plant extract should boost his natural telepathic abilities, allowing him to enter his companion’s dreamscape. Once inside, if he can persuade her that the reality she perceives is false, she may wake up safely. Hayton admits that it’s risky as much of what he proposes is based on theory and speculation and he hasn’t had an opportunity to test his ideas out, but the Doctor is keen to be his guinea-pig. In the meantime, he asks Ukarme to go back out and find his other companion Peri.

Peri knocks on Kyle’s bedroom door, but he refuses to let her come in. She tells him he needs to get dressed and go to school, but he says he can’t as he has a headache. In that case, she tells him he should take something and try to go back to sleep rather than lie around watching trash on the TV. He makes a sarcastic comment back to her, so she gives up.

Under the watchful gaze of the caged Jekyll, Hayton hooks both the Doctor and Erimem up to the laboratory monitors. Major Takol enters, having heard from Ukarme about the experiment that’s about to take place, and Hayton explains that the Doctor has volunteered to try out the plant extract. He injects the Doctor and then asks him to count backwards from ten. Within seconds, the Doctor is asleep and beginning his descent into dreamland...

First Minister Malarou reports to the Queen that the outer walls of the palace have been breached. Erimem asks whether Kharto can speak to the rebels to delay them, but Malarou tells her he’s currently unconscious in the cells. Erimem is resigned to the fact that the rebellion has succeeded, but Malarou insists that while she is free there is still hope. She may believe that she’s trapped, but at least it can be on her own terms. He reminds her of the panic room that was constructed in her quarters as a precaution. She’ll be safe there while Malarou rallies their troops to eject the rebels. Even if he fails, the panic room has a communications system and she can either negotiate or call offworlders for aid. Either way, she should be safe, but Erimem is concerned that while she’s in hiding, her country will be crumbling around her.

Ukarme confirms that the harvesting has been initiated as Major Takol requested. She tells him the shuttle is expected to arrive before nightfall and orders him to make sure they have enough samples to fill the hold. Hayton overhears the conversation and asks why Ukarme isn’t looking for the Doctor’s other companion as they agreed, but Takol tells him she has other priorities. Ukarme says the harvester’s safety override has cut in after detecting a foreign body, causing the equipment to go into emergency shutdown. Ukarme discovers the foreign body is the missing woman who was half buried in the plants. Looking at her now, it’s hard to tell where she ends and the plants begin. Hayton thinks this could be the breakthrough they’ve been waiting for, but he’ll need to examine the plant that’s consuming her. He tells Ukarme to bring the woman in, but asks him to use the harvester’s forward scoop to dig her up rather than cutting her free. Another alarm sounds, signalling that the Doctor’s delta waves are in sync with his friend Erimem and he’s about to enter her dream…

The First Minister shows Erimem to the panic room hidden within her quarters in the palace. She hopes it isn’t destined to become her tomb, but Malarou assures her he will not abandon her - but if something should happen to him, there is a secret door on the far wall that leads to an escape tunnel that will take her to a safe house. He hands her a file with more information and adds that the screens inside the panic room are patched into the security network so she’ll have full audio and video communications, including those offworld. She agrees to be sealed inside the room and seconds after the door is closed, the Doctor appears, claiming to have just arrived. Malarou knows no spacecraft have landed today and he demands to know how the stranger got inside the palace. The Doctor assures him he poses no threat to this world. Malarou introduces himself as the First Minister of the colony New Cairo of the planet Kandoor and the Doctor notices the ancient Egyptian décor of the palace. He finds Erimem’s subconscious fascinating, but before he can say anything, Malarou uses his communicator to summon the Guard. The Doctor says he only wants a quick word with Erimem and heads for the panic room, but the guards arrive and Malarou orders them to place the Doctor in the cells with his ’friend’ Kharto to see if that jogs his memory. As he’s dragged away, the Doctor protests that he’s here on a matter of life and death, but this convinces Malarou even more that he must be an assassin. He swears that the Queen will remain safe until their pathetic rebellion has been crushed.

Peri returns to Kyle’s bedroom and knocks on the door again. She tells him she’s made some sandwiches, but when he doesn’t respond she enters the room. Although the television set is playing “Love MD” at full blast, Kyle appears to be sleeping through it. Peri tries to wake him and realises straight away that he’s unconscious. His temperature is extremely high and he doesn’t respond to any of her attempts to revive him, so she picks up the phone and calls for an ambulance.

Ukarme returns to the base and arranges for Peri’s body to be brought to Hayton’s laboratory. The Professor is amazed to see that the kyropites are physically bonding with the girl’s skin, keeping her alive while simultaneously killing her. He hooks her up to the equipment and detects increased brain activity and a racing heartbeat, suggesting that she‘s experiencing something traumatic in her dream. Ukarme says he didn’t realise dreams could affect people’s bodies to that extent, but Hayton says the human brain is a very powerful thing and the relationship between mind and body is still very much a mystery. When Ukarme realises the plants have taken control of Peri and Hayton notes that the soldier isn’t as stupid as he looks. Takol arrives and asks about the new arrival and Hayton explains that she’s already entered stage three. The plant tendrils have started to bond with her skin and over the next 24 hours the cells in her epidermis will begin to mutate. After that, he suspects she’ll become some sort of human/plant hybrid, but he won’t know more until he’s run some tests. Meanwhile, there’s been no change to the Doctor and Erimem. Takol asks Ukarme to return to the harvesters as she wants the ship full of the plants and in orbit as soon as possible, but as soon she’s alone, she crosses to the unconscious Doctor and tells him that nothing must be allowed to delay the harvest…not even him!

The Doctor tries to break down the cell door, but it won’t budge. Kharto isn’t surprised and suspects it must be the stranger’s first experience of being in a prison cell. The Doctor assures him that isn’t the case and says he even had lesson in picking locks from Harry Houdini. He knows Kharto is the leader of the rebellion and asks what the revolt is all about. Kharto says the Queen is living in the past and is trying to turn the colony into a living museum, a recreation of their ancient home. It’s been nearly three millennia since the time of the Pharaohs and they’re hundreds of light years away from Earth so Kharto thinks they should be living in the here and now. The Doctor is determined to speak to Erimem and remembers Malarou saying she was safe in the heart of the palace. Kharto reveals that his brother helped build the palace and he offers to get the Doctor into the panic room if he’ll help him escape from the cell. He too would like to speak to Erimem as they have unfinished business.

In the hospital, Peri finds a pay phone and calls Mike. She’s surprised to find his mobile phone is switched off and although his colleagues in the office tell her he’s gone out, he isn‘t answering the phone at home either. She’s forced to leave a message on his answer phone. She tells him not to panic, but to come to St Peter’s Hospital straight away as Kyle has been diagnosed with meningitis.

The Doctor has been unable to find any weaknesses in the cell walls. He wonders how Kharto fits into Erimem’s world, but idea that Erimem created this colony all on her own makes the rebel laugh. Kharto points out there were twelve founders and thousands of colony ships, but when the Doctor asks him to name any of them or tell him where the ships came from, Kharto is unable to answer. He doesn’t understand why he can’t remember anything, but the Doctor says it’s too complicated to explain. He realises he’s never going to get through the locked door, but a passing reference Kharto makes about dreaming prompts him to try an experiment. If this is a dreamscape, the Doctor realises he should be able to manipulate it. He concentrates and, to Kharto’s amazement, the door opens of its own accord. The Doctor explains that it’s just a question of mind over matter and then leads he Kharto into the corridor.

Kyle wakes up and finds himself in hospital. Peri is by his side, but he’s disappointed that his dad isn‘t here too. Kyle is bitter that Peri didn’t believe how ill he was and she apologises, admitting that she made a mistake. Kyle drops back into unconsciousness and Peri wishes him sweet dreams.

In the panic room, Erimem uses the communicator to call for Malarou. Suddenly the exterior door to the room opens and she finds herself facing the Doctor. At first she suspects it’s some sort of trick, but then she accuses him of leaving her. He tells her the whole colony is just a dream but she thinks he must be mad and asks why she would dream about rebels, dead food tasters and servants betraying her. He explains that everything is being directed and controlled by parasitic plants on an alien world. Kharto races in and says there are guards are coming up the passageway. He offers to hold them off as long as he can and moments later they hear laser fire in the distance. Erimem is amazed to see Kharto free again and demands to know what’s going on. The Doctor tells her this place doesn’t make sense as it’s a mishmash of her old home on Earth and the kinds of frontier worlds she’d visited with him in the TARDIS. She insists that this is a Terran colony called New Cairo on the planet Kandoor in the Hyran System, but the Doctor knows there is no such system and never will be. He urges her to reject the illusion and asks her where Kharto got his laser gun from as he wasn’t carrying it earlier. He’s also noticed that it’s always the same two guards who keep appearing. Kharto calls out and tells the Doctor he can’t hold the guards off any longer, and then they hear him scream. The Doctor asks Erimem when Peri left, but she can’t remember the details. He explains that this was a detail her subconscious never bothered to establish, like the details about how this colony was founded. Malarou arrives with the guards and tells Erimem that the Doctor is a dangerous alien who is playing with her mind. He tells her to be strong and reject him, but she becomes suspicious when he talks about different realities. Malarou then claims the Doctor is a warlock who has cast a spell on her, but the Doctor explains that he’s using advanced alien technology and she admits that he sounds more like the Doctor she used to know. He asks her to close her eyes and listen to his voice. He urges her to accept that the room they’re in doesn’t exist and, in fact, she’s in a medical bed in a laboratory. He asks her to listen for an air conditioner in the room and feel the air as it passes over her sleeping body. As she does so, the protesting voice of Malarou becomes quieter and more distant. Then the Doctor tells her it’s time to wake up…

In the laboratory, the Doctor wakes up and calls to Erimem. Professor Hayton isn’t there and Ukarme says he had to leave. The Doctor asks his companion how she’s feeling and she tells him she feels like she’s been asleep for ages and that she had the strangest dream that seemed so real. He explains that they’re on the planet YT45 and Ukarme reveals that Peri is also alive and Hayton is looking after her right now. The Doctor asks him to keep an eye on Erimem while he goes to find Hayton, who has some explaining to do.

Still in the hospital, Peri is frustrated that she hasn’t been able to get in touch with Mike, so she tries ringing her best friend Ally instead. Unfortunately she doesn’t answer the phone either so Peri decides to go home and see if she can track Mike down from there.

Professor Hayton shows Peri’s sleeping body to Major Takol and says this proves his theory is correct - the process of absorption leads to a mutation in the DNA structure and changes are happening at a chemical level in the victim’s brain. Takol realises this gives them the means to unlock telepathic ability in humans. She congratulates Hayton on his work, then leaves to report the news to High Command. As Hayton prepares to cut Peri open to see what’s going on inside, the Doctor arrives and orders him to put down the laser cutter and move away from the patient. The Professor tells the Doctor there’s nothing he can do for his friend now. Peri is already well into stage three, but her death won’t be in vain and she can still be useful to Hayton as a subject for experimentation. The Doctor offers another warning, but Hayton refuses to let trivial emotional attachment stand in the way of scientific advancement.

Ukarme tells Erimem he was the one who found her out in the jungle. He’s glad to see her up and about, but she still feels very strange and she’s not entirely convinced that this isn’t just another dream. He asks her what it was like in the dream place and she tells him it felt totally real and she had no idea she was dreaming at all. She’s curious as to why he’s asking so many questions and notes that he doesn’t seem like any soldier she’s ever met before. Ukarme hints that there’s more to him than just his uniform and admits that he hasn’t been entirely honest with her. He produces a weapon and Erimem chastises herself for not realising earlier that he was being far too polite. She asks him whether he plans to kill her or take her prisoner…

Peri returns home and sees Mike’s car outside. Relieved, she goes inside and calls out to him, but there’s no reply. She hears voices and makes her way upstairs, but when she enters the bedroom she’s shocked to see her friend Ally in a state of undress with Mike watching. They both react with horror and offer to explain, but Peri refuses to listen to any excuses. She bursts into tears and races from the house…

The Doctor realises Hayton must have been planning to sell samples of the plant extract on the open market. The Professor says the mind controlling properties alone make it commercially viable, but now, thanks to Peri, he may even be able to isolate the chemical that stimulates telepathic ability. The Doctor tells him he won’t allow that and Hayton begins to suspect that he must be working for the Federation Drugs Administration. He dismisses the Doctor as a pen-pushing bureaucrat and says he always knew they would catch up with him eventually. He admits that he plans to bypass their ridiculously long and expensive drugs trials and make a fortune before they can do a thing about it. The Doctor reminds him that the military are funding this expedition and he wonders how they’re going to feel about him taking the profits himself, but Hayton says Takol and her High Command are all fools.

Peri wonders if this is what it feels like to die. Somehow she thought it would be quieter, but she can hear a loud bleeping noise…

Professor Hayton warns the Doctor that Peri’s vital signs are flat lining, which suggests some trauma or shock has befallen her in her dreams. The Doctor starts to fiddle with the controls in the laboratory, but Hayton warns him he could be doing more harm than good. The Doctor refuses to just stand by and do nothing, but Hayton isn’t interested in keeping this ‘specimen’ alive and wants to see how the plant will react when brain death occurs. The Doctor accuses him of being inhuman, which amuses the Professor in the circumstances. He pulls out a weapon and warns the Doctor to keep away, but before either of them can react, Major Takol enter the laboratory and shoots Hayton. She tells the Doctor that Hayton left the vid-link active, so she overheard every treacherous word he said. She intends to leave the planet before nightfall so she gives orders for Hayton to be confined to his quarters until the mothership arrives, then he can be transferred to the brig. The Doctor administers an injection of adrenaline to Peri’s sleeping body and she starts to stabilise. Her vital signs are recovering, but the Doctor still needs to get inside her dreams.

Peri wakes up and finds herself lying on the pavement outside her home. Mike tells her she was lucky as the car only glanced her. Peri is confused as she distinctly remembers the car hitting her full on and she’s sure she was as good as dead. Ally is calling an ambulance to take her to the hospital and Mike assures Peri that everything’s going to be okay.

Hayton is furious when he recovers and finds himself locked up. He tells Takol that he’s well-connected back home and she’s making a big mistake, but she reminds him that she’s in command of this mission and she won’t tolerate any insubordination. She closes the door to his quarters and locks the door. The Doctor asks if he’ll be secure there and Takol says there shouldn’t be a problem as long as they’re not still here after nightfall because that’s when the monsters come out. This planet has a diurnal cycle that lasts about 114 hours and during the day it’s a lovely place if you don’t mind the heat, the mud-slides and the murderous plants, but at night it becomes something else. The shuttle is due to land in about half an hour and Takol plans to evacuate 15 hours later. The Doctor realises he doesn’t have much time to get Peri out of her dreamscape.

Ukarme escorts Erimem at gunpoint to a door, and although it’s marked ‘Quarantine Area’, he assures her it’s safe. Inside, he shows her the remains of the original mission to this planet. She’s shocked to see that it looks like a disaster zone and Ukarme tells her the place was overrun by the Jekylls from the jungle. She didn’t think the creature in the laboratory looked too hostile, but he reminds her that not everything is what it seems. She asks him to tell her who he really is…

The Doctor and Takol return to the laboratory where he plans to set up the connections with Peri. He asks the Major to inject him with the plant extract and reminds her not to wake either of them up during the procedure. He also wants her to check on Erimem and although Takol assumes Ukarme is just showing her around the base, she promises to make sure she’s safe. They get to work as the sooner the Doctor can start his interface with Peri, the sooner he can help his friend.

In the hospital, Mike tells Peri that the doctor has said she was really lucky. In fact, there was hardly a mark on her so she can go home later tonight. Mike adds that he had Peri moved into the same room as Kyle, and although they’re not out of the woods yet, his son seems to be doing fine too. Peri regrets not taking Kyle’s illness seriously and thinks she makes a rotten stepmother, but Mike assures her he would have done exactly the same. He tries to explain what was going on between him and Ally and says it wasn’t what it looked like, but what was Peri supposed to think when she caught him in their bedroom with her best friend in her underwear. Mike tells her it was entirely innocent and was meant to be a surprise for her. Ally was trying on a dress that he’d bought for Peri. She’s sceptical as he’s never bought her a dress before, but he says he’s never had to plan a surprise wedding before either. Peri is stunned. Mike says Ally had been helping him with the arrangements and because she’s the same size as Peri, she’d been trying on the wedding dress to make sure it fit. Mike has been planning it for months was going to surprise her with the whole thing - a last-minute holiday to the Caribbean where he was going to propose and then present her with the wedding dress. Although this isn’t the way he wanted to do it, Mike goes down on one knee and holds out an engagement ring. He asks Peri to marry him…

Ukarme finally reveals to Erimem that he’s an undercover agent of the Federation Drugs Administration. Six months ago, a routine survey mission visited this planet and stumbled upon the unique properties of the indigenous plant life, the kyropites. They can’t be certain what happened here as parts of the survey report were missing and the data was corrupted, so even though they suspected a cover-up, they didn’t have enough evidence to act. There were no survivors, but he has a copy of the last message that was received from the survey crew. He plays Erimem a recording made by Captain Aranda in which she issued a warning to all space travellers to stay away from this planet. She explained that it was hostile and dangerous and she asked anyone who received this message to tell her family that she loved them. She said that when they landed they thought this planet was a paradise, but it turned out to be deadly due to the plants and the wildlife. Before Aranda could explain further, there was a crash followed the sound of screams and animal snarls. As she switches off the recording, Ukarme tells Erimem that Captain Aranda was his sister. The Jekylls killed the survey crew, then they shared their kill with the plants. Erimem realises the creatures as just as likely to attack them too and Ukarme confirms that they expect such an attack as soon as night falls, which is why their shuttle is due to land any moment. He now has enough evidence to compile a report on what Hayton has been doing here and he just needs to make sure it reaches his bosses back home. Erimem asks why he doesn’t just report his findings to Major Takol, but Ukarme says that wouldn’t be a good idea as she’s Hayton’s partner in all this!

Hayton and Takol pour themselves a drink to celebrate their success. Hayton wonders whether their charade of stunning him and locking him up in his cabin was really necessary, but Takol tells him she needed time to think. If the Doctor really does work for the FDA, she’ll need to think things through carefully. Hayton thinks killing him would have solved all their problems, but Takol says it’ll be far better if he dies in an accident. The important thing is that he doesn’t jeopardise their operation here.

Mike knows his marriage proposal has come as a bit of a shock to Peri and suggests he get them both a coffee while she thinks about it. In the corridor outside, the Doctor arrives and asks where he can find Ms Brown. Mike believes he must be the consultant who’s looking after Kyle and he proudly announces that he and Peri are soon to get married. The Doctor asks if he can pop in for a few minutes as the consultant has asked him to provide a second opinion, so Mike agrees.

Ukarme and Erimem return to the laboratory and find it empty apart from Peri and the Doctor lying unconscious on medical beds. Ukarme explains that Peri’s appearance is due to the plant life trying to bond with her and he says the Doctor is trying to get through to her telepathically like he did with Erimem. Unfortunately Peri is at a much later stage and it’s not going to be easy. Major Takol contacts Ukarme over the communicator and asks where he is and he tells her he’s checking the harvesters. When she orders him to return to the base immediately, he casually asks about the Doctor and Peri. Takol tells him there have been ‘developments’ and it transpires that the Doctor and his friends are hostile alien spies. She says they’ve both escaped so he should be on his guard and shoot them on sight. Erimem realises the Major has decided to show her true colours. Ukarme knows they can’t move the patients so the only thing they can do is make sure Takol and Hayton can’t get to them. They start to build a barricade by the door and Ukarme also overrides the door controls to lock them in. Just then, they hear the sound of the shuttle coming in to land. They realise they‘re running out of time, so whatever the Doctor is doing, he‘d better do it quickly

The Doctor enters Peri’s room, but when she doesn’t recognise him and thinks he’s come to check on Kyle’s condition, he realises things have progressed further than he’d hoped. He asks her to believe him when he tells her she’s in a dream and the hospital, her boyfriend and her stepson aren‘t real. She wonders what kind of a doctor he is, but he asks her to concentrate on him and tell him what she sees. She describes him as a chubby man with glasses and a nasty case of acne. He asks her to look again at his clothes and she sees a white coat with a stethoscope round his neck and a stick of celery on his lapel. She realises something is odd…and then suddenly remembers the Doctor!

The shuttle descends towards the planet surface and touches down right beside the base. Moments later, Professor Hayton supervises the robotic drones as they carry his priceless plant samples aboard the ship. Takol tells him to stay calm as she programmed the drones herself and they’re more than capable of transferring the samples safely. Hayton hadn’t realised how little time they would have. Nightfall is due in about ten minutes and Takol is keen to take off the moment the hold is loaded. Hayton goes to collect Ukarme and Peri as they’ll need her as a perfect specimen of someone in an advanced stage, but Takol tells him to be quick as she won’t wait for him.

In the hospital, Peri is confused as she remembers leaving the Doctor years ago. Kyle starts to wake up and calls for her. She’s delighted to hear him call her mum and he explains that Mike told him it was time he started getting used to her being part of the family. Peri tells the Doctor about her son’s brush with death and how she was hit by a car and then proposed to. Her life is complicated enough now without him trying to tell her it’s not real. Mike races in and Peri gives him the good news about Kyle. The Doctor tries to convince Peri this is all like a bad soap opera concocted by her own imagination, but Kyle turns to him menacingly and tells him to go away. Mike agrees and then finally Peri orders the Doctor to leave too.

Hayton arrives outside the laboratory and finds the door locked. He calls out to Ukarme, demanding to know what’s going on and ordering the soldier to open the door immediately. Ukarme refuses and reveals that he takes his orders only from the Federation Drugs Administration. Hayton says he always knew the Doctor was too stupid to be one of their agents and now he finally knows who the real spy is. They can hear the sounds of animals growling nearby and Ukarme warns the Professor to find a safe place quickly as it’s nightfall in the jungle and the Jekylls have probably got his scent by now. Hayton threatens to have the whole laboratory destroyed from space once he gets back on board the shuttle. Erimem suggests letting the Jekyll in the cage out, but Ukarme says it will rip them to shreds in a second. They hear the shuttle taking off and Erimem realises that if the plants in the cargo hold get off the planet, they’ll spread like a plague.

Aboard the shuttle, Major Takol makes contact with the mothership and speaks to Lieutenant Anders and tells her their estimated docking time is 30 minutes. Anders reports that their scanners are picking up an odd reading which shows some fluctuation in the shuttle’s engine performance. Takol hasn’t noticed anything, but Anders urges her to get to a life pod immediately. Takol accuses her of over-reacting and assumes it’s just a fault in the scanning equipment, but seconds later there is a massive explosion as the entire shuttle explodes just as it leaves the planet’s troposphere.

Outside the laboratory, Hayton begins shooting at the hostile primates as they advance towards him down the corridor. He calls out to Ukarme and pleads with him in the name of humanity to let him inside as the Jekylls are ripping the base to shreds. He explains that he went to the shuttle, but Takol had already taken off and abandoned him here. He even offers to help the Doctor and Peri, but the creatures are breaking in everywhere and he resorts to firing off random shots…

The Doctor makes another attempt to convince Peri of the truth. He tells her they’re both on an alien planet with Erimem and everything she’s experiencing here is just a dream. Peri doesn’t believe him and remembers Erimem being killed by crocodile-things. The Doctor realises she means the Krillian Horde, but he assures her they escaped from them. Mike threatens to get an orderly to thrown him out, but the Doctor says the orderlies don’t exist any more than the hospital does. He asks Peri to tell him about the moment when she left the TARDIS, but she can’t actually remember it. The Doctor points out that she ought to remember an important moment like that and Peri convinces herself that she must have lost her memory after being struck by the car. Suddenly there’s a huge explosion and Mike tells them a petrol tanker has just crashed into the hospital. He orders Peri to leave immediately and Kyle asks her to help him, but the Doctor says it’s just her subconscious doing everything it can to keep her in the dream. He tells her she has to give this life up, but Peri refuses to leave her family. The building starts to collapse around them and Kyle tells Peri he can’t make it without her help, then Mike collapses to the floor and tells her his leg has been injured. He and Kyle cry out for Peri’s help, but the Doctor insists that she has to choose a reality - this madness or her life in the TARDIS.

In the laboratory, Erimem urges Ukarme to let Hayton in as she’s sure they’re going to need his help. Ukarme insists that he’s a murderer who wanted Peri to die, but Erimem asks whether he’s any better? She reminds him there were people aboard that shuttle and she wonders if he gave them any thought when he rigged it to explode. He argues that the shuttle was piloted by an AI system and the only person on board was Takol, and after what she did here, he won’t be shedding any tears for her. However, he agrees to let Hayton in if that’s what she wants. He opens the door and Hayton thanks him, but suddenly the Jekyll in the laboratory escapes from its cage. It races towards them and Hayton grabs the gun from Ukarme and shoots the creature dead. Erimem is furious, but the Professor tells them it could have killed them all in ten seconds. He tells her they’re in the jungle and they have to learn to kill or be killed. Just then, the unconscious Doctor starts to mumble and Hayton agrees to revive him with a neural stimulant. Ukarme urges him to hurry as the barricade around the doors won’t hold forever. Unfortunately the stimulant doesn’t seem to work and the Doctor goes into cardiac arrest. Hayton tells the others to stand back as he tries electric shock treatment. Ukarme tells him if he fails, he’ll send the Professor back outside. The treatment only seems to be having a partial effect, but the semi-conscious Doctor asks him whether he tried both hearts. Erimem calls to him and eventually the Doctor revives and weakly, he tells her how pleased he is to see her again. On the bed next to him, Peri also starts to revive, although she calls out Mike and Kyle’s names. Erimem joins her and offers encouragement and then she too sits up and realises she’s back in the real world. The plant tissue around her body starts to fall away, but Ukarme tells them they don’t have time to make medical observations and they need to get out of her right now. Ukarme tells the Doctor that the base is made of a kind of plastic, so they should be able to cut their way directly through to the jungle.

Ukarme finishes cutting a hole in the outside wall and the group steps out into the night. It seems to be clear of the beasts but they need to get to the TARDIS quickly. Unfortunately he doesn’t know where the ship is, but Ukarme remembers finding them unconscious in some caves near Sector 4-North, so the Doctor asks him to take them there. Hayton asks about the Jekylls, but the Doctor says they shouldn’t have a problem if they’re quick as the creatures are too busy ripping the base apart to bother with them. Hayton asks for his weapon back, but Ukarme refuses and gives it to Erimem instead. The Doctor picks up the semi-conscious Peri and then they start to fight their way through the jungle. The vines themselves start to lash out viciously at them as they pass and the Doctor realises the plants aren’t going to let them get away without a fight. The creepers on the ground entangle themselves around Hayton, so Ukarme offers to go back and help him. The Doctor refuses to leave him, but Ukarme throws him his report and asks him to make sure it gets passed to the Federation Drugs Administration. Reluctantly the Doctor helps Peri and Erimem towards the caves just beyond the trees and seconds later they hear Ukarme’s screams as he succumbs to the effects of the plants. The Doctor asks Erimem to help Peri to safety while he goes back to rescue the others.

Sometime later, Ukarme wakes up in pain from a leg wound and finds his sister Aranda kneeling over him. She tells him not to move and promises her little brother that it’s just a sprain from when he fell. Ukarme is amazed as he thought she’d died, but she tells him she found a way to survive and she’s been here all this time in a hollow down below where the plants don’t grow. He tells he they don’t have to hide any more as they just need to find their way to the Doctor’s blue box. Aranda offers to help him to the TARDIS…

Inside the TARDIS, the Doctor and Erimem are at the controls when they hear a banging on the door. Erimem invites them in and leads them across the metal floor to the bridge. Ukarme explains that they managed to give the Jekylls the slip and introduces everyone to his sister Aranda. The Doctor says he’s heard so much about her and it’s a pleasure to finally meet her at last. He knows Peri would like to say hello too, so he asks Erimem to take Aranda down to the lower decks. He offers to show Ukarme around the nose cone of his ship, explaining that the rest of the ship buries itself on landing, leaving only the blue cone visible. The Doctor invites Ukarme and Aranda to join them and travel the galaxy as he always needs new crew members of their calibre. Ukarme accepts gladly and the Doctor gives him his first task - to press the launch controls and start the countdown. He starts to count from 10...9...8...7...

…6...5... In the jungle, Professor Hayton calls to the semi-conscious Ukarme and pleads with him to fight against the plants and not let them take over his mind. But it’s too late and by the time Ukarme mouths the words “lift-off”, he is completely under the kyropites’ influence.

“Memory zero, negative. Reset." Peri wakes up with a start and finds herself alone in the dark. She calls out to anyone who can hear her...

Peri walks out onto a small wooden bridge where she joins the Doctor looking out over a stream. It’s been a nice night so she wonders why he came outside to be on his own. She asks if the party’s been too much for him or if he’s contemplating jumping in, but he doesn’t respond. She calls out loudly and he jumps with a start, not realising she was there. He admits that he thought it best to leave her, since she was having such a good time. His mind is obviously miles away but oddly he can’t seem to remember what he was thinking about. She laughs about his old age, but he just repeats her words distantly. Something is obviously wrong and he starts to feel very strange. Peri wonders if he’s had too much of the Grallistan punch and as he continues vacantly repeating her words, she concludes he must be the worse for wear. She reminds him that it was his idea to come here and he said she needed to relax and enjoy herself. The Doctor suddenly cries out in agony and then his face begins to physically transform. Peri starts to panic and she calls out for someone to help, but there’s no reply from anyone inside the party. Within seconds, the Doctor’s transformation is complete and he stands up. Now his appearance and voice make him an exact replica of Peri herself. Confused, Peri looks around for the Doctor and then races back to the house.

“Recall and delete.”Peri wakes up with a start and finds herself alone in the dark. She calls out to anyone who can hear her and asks them to turn the light on, but a voice responds telling her there is no light that she can see, but there is light beyond her visual spectrum that she can‘t see. The voice asks her what it was she was just remembering, but Peri is confused by the question as she’s sure was asleep. She refuses to answer on the grounds that dreams are private and instead, she asks who the voice belongs to. When the voice changes into a replica of her own, she thinks it‘s some kind of trick and bangs on the wall and asks where she is. She hears her own voice, repeatedly asking her to remember, but Peri thinks her captor is just trying to freak her out. The voice returns to normal and asks whether she remembers all this happening before or whether she can remember what happened immediately before she woke up. The voice advises her to be honest in her reply as it’s the only way they can be sure. Peri asks who they are and why they keep pretending to be her and the voice tells her they are the Viyrans. The voice asks if she remembers the Doctor, but she refuses to answer the question. The voice tells her she has left them with no choice…

Peri races back into the party and calls out for help. She gets no reply and the music is deafening, so she switches it off. It suddenly dawns on her that everyone in the room is lying on the floor, as if asleep. She crosses over to a face she recognises and tries to get the man to wake up. She slaps his face and Chris asks her what’s going on. She tells him something strange has happened to the Doctor, but she’s not even sure if what she saw was real. Everyone here in the party seems to have flaked out too, perhaps from drinking too much of the punch, and no one else is awake apart from Chris. She tries to persuade him to come with her, but then he starts to vacantly repeat her words and then physically transforms before her eyes into a duplicate of herself, just as the Doctor did earlier. Then one by one, everyone else in the room wakes up, begins copying Peri’s words and then they too start to change their appearances. Peri screams…

…and then wakes up again in the darkened room. She calls out to the voice she was speaking to earlier and demands that they stop playing games and tell her what’s going on. The voice explains that her brain activity shows she was remembering something and they must know what it was. Peri can’t understand why they don’t already know, since they’re monitoring her brain. The Viyran confirms that they can’t read minds, but if she’s remembering something they need to know what it is as a matter of urgency. It’s says it’s better if Peri doesn’t know why and it would be simpler if she just trusted them. The voice refuses to answer any of her questions, so eventually Peri admits that she did remember something. She asks if they’re going to hurt her if she doesn’t tell them and says she’s never going to trust them if they threaten her. She tells them she was at a party on Grallista Social and she noticed the Doctor had left. She again asks who the Viyrans are, but they say they can’t tell her anything further as this would require building significant new memories. Peri refuses to accept this and the voice eventually agrees to one concession in order to earn her trust. He explains that they already know of her memory because she’d already told them about it before. In fact, she’s told them 337 times previous to this treatment period. Peri is shocked to discover she’s being ‘treated’ for something, but the voice tells her memories are not always in chronological order. Peri says she remembers Erimem and the voice tells her that memory is permitted, but asks her what is the next thing she remembers relating to the planet Grallista Social.

Peri thinks hard. She remembers going back into the party hut to get help, but when she got there she found everybody was lying down, as if unconscious. She woke Chris up and he spoke, but she’s not sure she can remember what happened next. It was weird and she remembers remembering it like a dream, but the next thing she remembers is something about having a son called Kyle. She’s not sure if that’s true, but the voice can’t help her as it’s for her to decide what’s real or not. Peri realises that it’s possible her memories about Grallista Social and the Doctor transforming into her might not be true either. Then she remembers Dracula and losing the TARDIS, but the Viyran wants her to concentrate only on Grallista Social and what happened when they first arrived on the planet…

The TARDIS materialised and the Doctor and Peri emerged. She was amazed that the people here actually called their planet Grallista Social and the Doctor explained that they did this so visitors would know what to expect when they came here. Peri wasn’t sure she was in the mood for socialising, which is precisely why the Doctor thought they should come here and socialise. He thought they’ve had enough heartache recently and it was time for them to unwind. Peri noticed that the people here weren’t particularly fazed by a blue box appearing out of nowhere. The Doctor told her that in fact nothing ever seems to faze people on Grallista Social so they should take a leaf out of their book and relax. He recommended she have a nice time, meet new people and most importantly, taste their infamous Grallistan punch. Suddenly Peri started to cough and retch, as if she’d just swallowed a fly. She was certain she’d felt something hit the back of her throat, but there seemed to be nothing there now even though her throat was a little numb. The sensation faded…

Peri remembers everyone’s face changing until they all looked like her. It was like a nightmare and she thought she was going mad. She just wanted to wake up and get away. She remembers running out of the hut and climbing into a nearby vehicle, then pushing every button until it started to move. She found the accelerator and drove as fast as she could until she could see the lights of the party a long way behind her. She didn’t know where she was going or even what she was trying to get away from. Then suddenly her headlights caught a man up ahead in the road, and although she slammed on the brakes, she couldn’t avoid hitting him. She climbed out and apologised to the man on the ground, but fortunately he didn’t seem badly hurt and he didn’t have any broken bones. She kept apologising until he asked where she came from, and when she told him she was in one of the party huts he observed that it must have happened there too. He assumed she must have been trying to get away, given the speed she was driving, and he told her he was also trying to get away, but in his case from the spacepad. She told him it was good to see a friendly face, or at least a different face, and then the man pointed out a strange noise coming from the direction of the party huts. Suddenly a ball of bright, shiny light approached at great speed and then flew over their heads before disappearing. Then another one flew overhead and they noted that they were heading in the direction that the man just came from. The man said they must be connected to the creatures at the spacepad in some way and when Peri got confused he said he assumed that’s who she was trying to get away from. Before she could explain further, more balls of light flew past and just for a moment Peri thought she could see people inside them. On closer examination, the balls were actually coffin-shaped and appeared to be made of glass. The man introduced himself as Lawrence and Peri told him something seriously weird was going on here. She asked him what it was he saw at the spacepad and he pointed to something behind her. She turned and asked if these were the creatures he was talking about. Before he could reply, he started to change in front of her and in seconds he had taken on Peri’s own voice and appearance, just as the others did earlier. Peri screamed…

Inside a dark empty room, Peri bangs on the wall and demands to be released, but then her own voice is played back to her, increasingly louder and faster until she can’t bear the noise any more. Then her own voice announces that the language has been assimilated through a recording of her voice as her species has never been encountered before. It tells her they’ve been searching for her and refers to her as patient zero. Peri can’t cope with looking at an alien that speaks with her voice, so the being starts to adopt a male voice instead. The alien explains that they are the Viryans and Peri is patient zero. When Peri becomes confused, the alien wonders whether they’ve assimilated the language correctly and admits that they are forced to speak to her artificially because they have no vocal language. Peri knows that patient zero is a term used to define the first person infected by something and the Viryan confirms that she has understood correctly. He adds that it’s not necessary for her to know more and their aim is simply to cure her and then wipe her memory of the whole incident. An extremely bright light shines down upon Peri, causing her considerable pain. She begs for it to be switched off and then screams in agony…

The Doctor recognises Chris from when he and Peri met him earlier. He asks if he’s seen her recently and Chris explains that he hasn’t seen her since last night, but he admits that things did get a little hectic at the party. The Doctor says he left early, but he seems sure the party was longer ago than last night. Chris put this down to the effects of the punch and he suggests the Doctor go back to bed and sleep it off. The Doctor assures him he feels fully rested, but he’d arranged to meet Peri this morning and she hasn’t shown up, so he’s getting worried about her. The last thing Chris can remember is Peri leaving the party to find the Doctor with the intention of dragging him back, but she never returned and the Doctor can’t remember whether she ever found him. Chris tells him there’ll be another party tonight, but his advice to the Doctor is that he gives it a miss and settles down instead with a nice cup of chocolate and a boring book.

“Memory zero, negative. You have remembered more again.” Peri is confused as the Viryans seem to be trying to get her to forget something, but the problem is she doesn’t even know what it is she’s not supposed to remember. The Viyran explains that after neutralisation and inoculation, they attempted 338 times to achieve memory zero. During the first 227 attempts her memory decreased significantly, but after that her memory started rebuilding itself further at each attempt, which means she’s now ended up remembering more than she did before they started. The Viyrans’ time here is limited and any attempt to continue this experiment will clearly be pointless and may even provoke further recall, so now they’ve decided to ‘expunge’ her and the Doctor. They explain that as patient zero, her lack of memory will prevent the Doctor rebuilding his memory while she is with him, but during the times when she isn’t present, there’s too high a risk that the Doctor will start to remember things. For this reason, they must both be expunged. Peri suddenly has another idea and she asks whether she ever really understood, at any stage, what had happened to her. The Viryan says she never did as any explanation would be outside her frame of reference and they deliberately sought to preserve those areas of ignorance. Peri argues that because she never understood what happened in the first place, she was left with too many nagging questions in her mind. Each time they tried to assess how much memory she’d retained, she started trying to work out which bits she‘d forgotten. She suggests that it might work if she actually wants to forget…

The Doctor returns to the TARDIS and is surprised to find Peri is already inside waiting for him. She asks if he’s okay as he looks worried and he admits that he doesn’t really know what to think. Peri claims that they’d previously agreed to meet back inside the ship and although he can’t quite remember, he accepts her story. She asks what he got up to last night after he left the party and he seems surprised that this was only last night. When she suggests he may have had too much of the punch, he asks her what exactly happened the last time she saw him.

Peri walks out onto a small wooden bridge where she joins the Doctor looking out over a stream. It’s been a nice night so she wonders why he came outside to be on his own. She asks if the party’s been too much for him or if he’s contemplating jumping in, but he doesn’t respond. She calls out loudly and he jumps with a start, not realising she was there. He admits that he thought it best to leave her, since she was having such a good time. His mind is obviously miles away so she asks him what he’s thinking about, but oddly he can’t seem to remember. She laughs about his old age and reluctantly he agrees. He says he might just go back to the TARDIS, but Peri says she promised Chris she’d drag him back to the party. The Doctor is sure Chris would rather have Peri to himself, so he arranges to meet her back at the ship the next morning.

Back in the present, Peri assures the Doctor that’s exactly what happened. The Doctor seems unsure, but then when he thinks about it he can’t even be sure why he brought the subject up. He asks if she enjoyed herself last night and she says she had a great time but she still feels sad about Erimem. The Doctor knows Erimem wouldn’t want them to be sad and although it won’t be easy to get used to travelling without her, there’s a whole Universe of time and space out there waiting for them. Peri says she’s ready to leave if he is, so the Doctor sets the controls and the TARDIS dematerialises.

The Viyrans come from another galaxy, one that has known only war for millennia. Finally the fighting ended and a treaty was signed for the cessation of all biological warfare, but during the decommissioning there was an accident. Countless viruses and biological agents engineered for every conceivable purpose were released and scattered across the cosmos, allowing particles carrying disease and death in a myriad of forms to spread out across the stars. One such particle entered the atmosphere of Grallista Social - an invisible mutagenic particle which infected Peri and caused her to become patient zero.

The Doctor recommends she should have a nice time, meet new people and most importantly, taste their infamous Grallistan punch. Suddenly Peri starts to cough and retch, as if she’s just swallowed a fly…