Aboard his ship, Commander Gammades prepares a letter to his love, the Lady Vuyoki. He asks her why she’s so coy, especially as they’re both equally trapped on this godforsaken rock. This is a place where time sluices all around them and the past and the possible dash against the reef. He pleads with her to join his crew as he fears for her safety with monsters lurking in the gullies and cracks of their prison. He says their enemy, the Ruhk, is both foul-hearted and cunning and warns her to avoid it all costs. He admits that his crew are rough voyagers, but his ship is sound and efforts are being made to cut her free from the coral that binds them here.

He’s interrupted by Captain Lucor who tells him Eumachus has gone out onto the reef and launched himself off the ridge attached to a line drum. Despite the danger, he’s taken the beacon with him and it looks like he’s trying to reach the surface. Outside the ship, Eumachus has donned an opposable gravity suit and is instructing his colleague, Coris, to reel out the line attaching him to the drum on the edge of the ridge. Then, like a kite, he starts to fly up high into the sky. Gammades speaks to him over the coms system and orders him to return as he’ll get them all killed. More importantly, he may lose the beacon in the process and it‘s already cost them enough. Eumachus points out that the beacon doesn’t work down on the ship, so he thought he’d try it up near the surface.

From his vantage point above them, Eumachus can see the whole reef and reports that it’s growing faster than they thought. At this rate it won’t be long before it fills the whole bubble. Gammades agrees to let Eumachus continue so long as he takes care not to burst the bubble around them. In any case, since the Ruhk stole all their goats, they’ve been unable to make any sacrifices. Eumachus tries the beacon, but gets nothing and mocks Gammades for buying faulty equipment.

Suddenly the crew spot a shadow crawling up the ridge in the distance. Gammades identifies it as the Ruhk, that evil broken-winged night bird, and he shouts a warning to Eumachus. Coris starts to reel his colleague in, but the monster is closing in on its target. Gammades suggests using the harpoon, but it’s pointing in the wrong direction and there won’t be time to swing the ship round. Before anyone can act, the Ruhk swoops down to attack Coris and the crew hear his scream as he’s knocked over the ridge and disappears into the distance. Gammades promises Eumachus they’ll bring him back down, but by then it’s too late as the Ruhk grabs hold of the line and begins hauling him in. Believing the creature’s after their beacon, Eumachus cuts the line and seconds later the crew see him floating away. Gammades warns him to keep clear of the surface and not to touch the vortex - but the warning comes too late and the communicator fills with the sound of static. Lucor spots Eumachus knocking against the surface of the vortex, but it seems he’s still alive as they can hear his voice calling down to them. Gammades warns Eumachus that he’s starting to drift away, but a terrible thought occurs to Lucor. Although they can hear Eumachus calling down to them, it’s simply his last moment repeating itself. Eumachus is both dead and dying, over and over again. Gammades is furious and curses the Ruhk and the reef - but most of all he curses the Doctor who brought them to this place and abandoned them to their fate!

Having recently been reunited with his TARDIS, the Doctor has been exploring the corridors and has found things are not as he left them. In particular, the usual route to the spare equipment store no longer exists and junctions he was previously familiar with are not where they should be. Nyssa believes they’ve simply come the wrong way, but the Doctor knows things aren’t right. Even the engines sound wrong and for years there’s been a rattle whenever the ship took off, but now it’s gone, only to be replaced by different rattles. The Doctor is convinced that their other companion, Thomas Brewster, is responsible and it dawns on him that he has no idea where Thomas went in the TARDIS during the five months he and Nyssa were marooned. The Doctor finds a door where there shouldn’t be one and he warns Nyssa not to open it in case it leads to the Power House, or even directly to the Vortex. She tries it anyway and they’re both shocked to find themselves back in the control room.

At the console, Brewster is surprised to see them as he wasn’t expecting them back so soon. The Doctor and Nyssa both realise it’s impossible for the corridor they were in to lead to back here, which means someone’s been messing about with the inner dimensions. Brewster protests his innocence but the Doctor guesses there’s a lot he hasn’t told them about where he went after abandoning them in London. Nyssa points out that in Brewster’s timeline he may have only been gone for five minutes, but the Doctor says the evidence suggests otherwise. He also notices Brewster is wearing one of his own shirts but the boy says he found a cupboard full of clothes in all different sizes and they can’t all belong to the Doctor. Nyssa goes to get the Doctor a cup of tea to calm him down, but he warns her to be careful as the dimensions outside the control room aren’t stable. The Doctor knows that launching out into time and space on your own can be a unnerving and terrifying experience so he tries to be more sympathetic to Brewster. He decides to run a full fault check to see what the damage is, but he discovers the entire fault locator unit has vanished. Nyssa returns and reports that the food machine has gone too.

Alone on her own ship, Lady Vuyoki occupies her time by singing to herself while residing inside a huge glass jar. Her solitude is interrupted by a visit from Captain Lucor, bearing a recorded message from Commander Gammades aboard their ship, the Gamma. She finds the intrusion irritating and treats the Captain with the same contempt she shows everyone below her station in life. She plays back the message and although she laughs at Gammades’ amateur poetry, she finds his invitation for her to shelter with them touching. She prepares to record a message in return…

None of the readings aboard the TARDIS make any sense, so the Doctor decides to explore further into the ship. They don’t know how much damage Brewster’s done so he unwinds a ball of string - enough to take him as far as the auxiliary junctions - and gives Nyssa and Brewster instructions that if he tugs twice, they’re to haul him back quickly. He opens the inner door and as it looks safe enough in the corridor outside, he soon disappears from sight. Once they’re alone, Nyssa asks Brewster what else is missing and points out the whole inner structure of the TARDIS is destabilising. He denies any knowledge and accuses her of acting like a princess, but he also inadvertently admits that he knows a proper lady who owes him a lot of favours. When Nyssa asks where he’s been all this time, he tells her he went to hell and back. Suddenly the Doctor’s voice calls out from the corridor, begging Nyssa to help him. They look through the door and see the passageway on the other side is sliding around as the dimensions fold in on themselves. They rush to pull the Doctor back…

Commander Gammades listens back to the message Lady Vuyoki recorded for him. She thanks him for his most generous offer, but she declines it as he’s simply a rough voyager and a lady of Maribu like herself could never see him as anything more than a servant. She pledges to remain on her ship alone, lamenting the fact that he can never be part of her newborn life. Vuyoki’s rejection simply convinces Gammades even more that she’s a woman of spirit and determined grace, and he swears to himself that one day they’ll be together.

Nyssa and Brewster pull hard on the string, but the corridor outside is pitch black and they can’t see anything beyond the door. Just then, the Doctor’s hand emerges and Nyssa grabs it, noticing that it’s freezing cold. She can’t hold on and the Doctor disappears again, apparently lost to them. Ignoring Nyssa’s warnings, Brewster plunges his own hand into the darkness. Fighting against the pain of the cold, he feels around until he finds the Doctor’s hand and then, with Nyssa’ help, they drag the Doctor back out into the safety of the control room. They start to recover and the Doctor, still covered in ice, weakly thanks Brewster for his bravery. He tells them the relative structure of the TARDIS is in flux and is breaking down. Nyssa suggests using the conceptual geometer to map out the interior, but when the Doctor checks, he discovers that’s missing too. He turns on Brewster again and accuses him of selling off his equipment in return for cheap gin and a pie. He checks the memory banks to find out where the TARDIS has been and Brewster argues that his privacy is being invaded and begs the Doctor to stop. However, the readings don’t seem to make any sense as there are no spatial or temporal locations listed. This doesn’t stop the Doctor programming the ship to return to its previous destination.

An alarm sounds aboard the Gamma and Gammades’ crew run around in panic and confusion. Captain Lucor tries to pinpoint the source, but the Commander thinks it must be the beacon returning. Lucor confirms that Eumachus is due to orbit around them any time now. Right on cue, their dead colleague appears on the horizon and they hear his last words repeating themselves again. The alarm must mean the beacon is finally working, so Gammades offers a reward to the first man who sights their rescuer. They can see the Vortex in turmoil above the surface of the bubble and it looks like it’s building up into a huge time storm. Lucor warns the crew to go below deck and tells them to expect heavy weather. Gammades hopes it will blow the Ruhk away too. Then they hear the sound of the TARDIS materialising and they realise the Doctor must be coming back!

Inside the ship, the systems are registering imminent structural collapse. They can hear the alarm from the beacon and at first the Doctor believes it’s coming from another TARDIS, but as the inner walls start to rupture, he realises the sound is his own missing conceptual geometer calling to them. He sets the controls to home in on the signal, but Nyssa says it’s too late as they’re on a collision course. The three of them hang on tight as the TARDIS crash lands…

They evacuate the ship before the interior collapses and then everything goes quiet. The Doctor reveals that the whole internal structure of the TARDIS has imploded after the interior dimensions compacted and crushed down into a single knot. His ship is dead and there‘s nothing anyone can do about it. The Doctor is in a state of shock and Nyssa explains to Brewster that it’s like he’s lost an old friend. They find themselves standing on a barren unwelcoming rock, like being on the surface of an asteroid but without a sun or stars. Nyssa realises Brewster has been here before and the Doctor demands to know what he has to say for himself. Nyssa decides to leave them to speak alone and the Doctor warns her not to wander off too far. He tells Brewster they’ve landed on a reef of space corals, stuck in a bubble of existence where nothing can exist. He doesn’t know how the reef got here, but it feels like they’re underwater as they can see the energetic patterns of the Time Vortex playing across the surface of the bubble above them. The Doctor spots broken pottery which suggests the place is inhabited and he identifies the design as possibly coming from one of the late dynasties, like Maribu.

Suddenly Eumachus appears on the horizon and flies over them, still wearing his spacesuit and calling down his last words again. The Doctor assumes it must be a friend of Brewster’s and he waves back. Brewster tells him to stop and the Doctor wonders whether he’s scared of attracting trouble. It’s too late and from out of nowhere, Commander Gammades and his crew appear and confront the two men. Brewster tries to escape, but they grab hold of him. Gammades taunts the boy for abandoning them and suggests staking him out on the rocks for the Ruhk to feed on. Then he demands to know who the Doctor’s friend is…

Commander Gammades says the Doctor was the last person they were expecting to see again, but when the Doctor queries whether they’ve ever met before, Lucor orders him to be quiet. It becomes immediately clear that the crew are all of the opinion that Brewster is the Doctor, so the real Doctor decides to play along to see what he can find out. Gammades accuses Brewster of lying to them and trading them damaged goods before deserting them to their fate. He says the ‘Doctor’ lured their ship to this rock and stranded them here, but Brewster insists he only went away for a while and always intended to come back. Gammades plans to commandeer the TARDIS, but Brewster protests and claims that he brought his friend back with him to help as he has all the answers to their problems. Then Brewster makes a run for it and Gammades orders his men to chase after him, but they refuse to go down into the gully because that’s where the Ruhk lives. The Doctor suspects they must be talking about an indigenous species, but Gammades describes them only as “damned carrion birds” that prey on them. The Doctor realises Nyssa may be in danger, but they refuse to let him go after her. The Commander demands that he open up the TARDIS, but the Doctor claims that only the ’Doctor’ has a key and he doesn’t share them with his companions. A guard is placed on the TARDIS and Gammades orders the Doctor to be brought back with them to their own ship.

Nyssa tries to get away from the huge bird creature, but it grabs hold of her and demands that she fetch the beacon as it “sings this place alive”. The Ruhk refers to the ’blinding dark’ and Nyssa realises the creature can’t see her. It tells her it can sense her fear in its mind and it reveals that this place is a trap and the beacon lured it here with its beguiling light and symmetry. This is a heavy, crushing place and the Ruhk wishes to pull the beacon apart to prevent any others of its kind from dying. The strange noise Nyssa heard earlier is actually a herd of goats and the Ruhk says they were born to be sacrificed. He tells her the beacon is with the Commander so she promises to find him if she can.

When the Doctor is brought aboard the Gamma he finds the crew are busy clearing coral away from the hull. The Commander orders them to stop work, confident they’ll soon be leaving in the TARDIS, and he grants permission for an extra round of grog to be handed out by way of celebration. Lucor is surprised he’s planning to abandon their ship, but he tells them they’ll salvage what they can before they leave.

Brewster finds himself returning to Lady Vuyoki’s ship. He taps on the side of her jar, but she’s not entirely sure she’s pleased to see him again. He reminds her that he said he’d turn up again, but she says there’s always such a long time between visits and she has nothing to occupy her time except sit in her bridal jar and chew on dried bar of porpoise scrapings. She’s also disappointed that on this occasion he hasn’t brought her any presents, but he promises to bring something next time. She believes everyone here is already dead, condemned to their own individual torments and waiting to be reborn. They hear a noise outside and Vuyoki climbs back into her jar and asks Brewster to secure the lid. Then he turns to see off the intruder…

The Doctor is taken to Gammades’ cabin and takes an interest in a photograph of the Commander’s family. One of the perils of time travel is that his sons will be as old as he is if he doesn’t return home soon. The Doctor has recognised the Gamma as one of the galleys belonging to the classical pioneers of trans-temporal voyaging. Gammades regards himself and his crew as heroes who’ve sought adventure across the ages and are now returning from some magnificent campaigns. When they began their journey home the ship was full of booty, but as they slid between the shoals of time they heard a cry for help. Ignoring the possibility that it might be the sirens, they came to the aid of what they thought was a wretched mariner, cast adrift in eternity. Before they knew it, they found themselves wrecked on this uncharted reef. The ‘Doctor’ was already on the reef when they arrived and he was touting for business with the TARDIS set out like a market stall, so Gammades traded with him even though it cost a large chunk of their treasure trove. They bought a temporal navigation unit, a fault locator, a food machine and a beacon, which the ‘Doctor’ claimed would help them attract rescuers. Unfortunately none of it seems to work and the ‘Doctor‘ soon left them stranded. The Doctor isn’t surprised as his equipment wasn’t designed to be compatible outside the TARDIS. He also reveals that the beacon is actually the alarm from a conceptual geometer. The Doctor reveals his true identity and insists that he gets all his equipment back. Gammades refuses and says it was all paid for fairly, but the Doctor points out that with the geometer back in its proper place, the TARDIS might still be functional. Gammades tells him the reef isn’t very big, but it’s still growing, so the Doctor decides to explore outside.

Nyssa arrives at Lady Vuyoki’s ship and is surprised when Brewster emerges from hiding. He claims he was sent by the Doctor to find her and asks why she’s being followed by a flock of goats. She tells him they were showing her the way and as she’s looking for the Commander, she assumes this must be his ship. She’s curious about the big jars that fill the room, but when she opens one up it reveals Lady Vuyoki. Brewster introduces them and Nyssa realises this must be the ’proper lady’ he mentioned earlier. Vuyoki is far from impressed by Nyssa and assumes Brewster intends her to be a gift, a slave to serve her during her confinement until she heads for her new life. She points out that her own slaves are fed on mud so they know their place, but Nyssa insists that Brewster explain the truth. Just then they hear the Ruhk outside and Nyssa realises it must have followed her. Vuyoki accuses Nyssa of bringing the misshapen fiend to her sanctuary and curses her.

Gammades tells the Doctor that when he was newborn he was taken to an Oracle who foretold his death in glorious battle. His first ever toy was a sword and all through his schooling he was told he was going to be a hero - but now he’s resigned to the fact that he’ll never meet his doom. At the burning of the Sable Empire, a wounded Sphinx came prowling through the field of dead and found him where he lay bleeding. She cursed him to eternal life - the worst possible fate for a hero who was trained to die in combat. The Doctor tells him that in his experience, fortune tellers only ever tell half of what they mean. Gammades believes the gods are mocking him by trapping him outside time in a bubble of endless now, but with the Doctor’s TARDIS they have hope again. His people haven’t offered any sacrifices for 130 days since the Ruhk stole their goats, but this intrigues the Doctor as it means the Ruhk is rational and not just a wild beast. The Doctor objects to the principle of blood sacrifices and the Commander wonders how he ever gets anything done. He points to the wreck of another spaceship in the distance and says there’s just one survivor there - a lonely lady who rules Maribu. The Doctor knows of the Grand Maribu and wonders how she could ended up here as her dynasty rules at the other end of time to Gammades. The Commander says he’s vowed to rescue her from this prison, but this deeply worries the Doctor. Over the next crest they spot the TARDIS not far from the Gamma, which means it’s only taken them an hour to walk right round the circumference of the reef and come back to where they started.

Nyssa tells Brewster she‘s going outside to talk to the Ruhk. He and Vuyoki try to stop her and tell her the creature only feels hate and anger, but she believes it’s simply lost and confused. Vuyoki appears to change her mind and agrees to Nyssa’ suggestion, but only because she thinks the Ruhk will go away once it gets what it wants. Brewster asks if there’s another way off the ship and Vuyoki opens the hatch to the loading port and the gully outside leads directly towards the Gamma. Brewster and Nyssa prepare to leave, but Vuyoki stays behind, saying she’s dealt with the Ruhk before. As soon as she’s alone, Vuyoki opens the main door and tells the huge bird creature that Nyssa called it a misshapen fiend. She also reveals that she’s tricked the girl into heading straight for the Ruhk’s nest and it can still catch her if it hurries...

Gammades and the Doctor approach the TARDIS and are surprised to find that the guard has abandoned his post. The Doctor notices the coral has already started to grow up the sides of his ship and Gammades confirms that one day the reef will fill up the whole bubble. The Doctor decides it’s time the Commander knew the truth about himself and this place, but before he can say anything they’re interrupted by Eumachus who, regular as clockwork, appears on the horizon and calls down to them. Gammades explains that Eumachus was the ship’s apprentice hero who died trying to get the beacon working. When he cut his own line to escape the attacking Ruhk, he touched the surface of the bubble and got pinned to the sky. Unfortunately that’s where the Doctor’s conceptual geometer is too, way out of anyone’s reach. The Doctor opens the door of the TARDIS and lets the Commander see inside. It’s dark, like a void, because it has no dimensional structure. The ship is effectively dead unless the Doctor can get his geometer back. He reveals that he is the real Doctor and that Brewster stole his TARDIS and caused all this inconvenience. The reality bubble they’re trapped in is generated by the conceptual geometer, churning up time and space. It takes just one stray polyp of space coral on the TARDIS shell to create a reef like this that’ll wreck ships and strand innocent lives. Gammades believes this makes their current situation all the Doctor’s fault.

Brewster and Nyssa head away from Lady Vuyoki’s ship, but they reach a dead end and Nyssa suspects they‘ve been tricked. Although they’ve been following Vuyoki’s directions, they don’t seem to be leading anywhere. Brewster believes the rocks ahead are just tangled over, but it looks more like a nest to Nyssa. They hear the goats approaching, followed by the sound of the Ruhk. Brewster wants them to hide before they’re spotted, but the Ruhk lands in front of them and tells Nyssa it can hear and smell her. It accuses her of betraying him…

Gammades arrives at Lady Vuyoki’s ship and knocks on the door. She sighs and wonders whether the Commander will ever take no for an answer, but Gammades says he wants her to meet the Doctor. Vuyoki is overcome when she sees him and asks whether her wait is finally over. She believes he’s the all-knowing spirit known as Old Birth, who leads the unborn to their new lives. She assumes he must have cloaked himself in human guise to shield her from his glory and she assures him she’s spent every solitary moment contemplating her past sins and is now ready to be led to her new life. The Doctor explains that he’s looking for two friends and Vuyoki reluctantly admits that they may have passed through recently. Gammades points to the jewels Vuyoki is wearing and tells her they’re part of his booty from the sacking of the Sable Empire. He asks how she came by them and she reveals they were a gift from Brewster, but the Doctor is more intrigued by the hieroglyphs on Vuyoki’s bridal jar. Gammades is still in love with her and takes the opportunity again to make her an offer to join them aboard the Gamma, but once again she rejects him and tells him to leave and take the Doctor with him.

As the Ruhk searches for Nyssa, Brewster urges her not to move, but she says she‘s already made a promise to the creature. She steps forward and tells the Ruhk she simply hasn’t had time to find the Commander yet. Brewster tries to protect Nyssa, but the huge bird knocks him to the ground with one swipe of its wing. Just then the Doctor arrives and calls for the creature to leave his friends alone. Nyssa tells him the Ruhk is trapped and alone and she doesn’t think it belongs in this dimension. The creature says it comes from an eternal everness of flying free and normally its feet would never touch the ground, but the dimensions here bind and crush it. Suddenly, Commander Gammades appears with his men and they charge towards the Ruhk. There’s a brief struggle, but the creature is overpowered by the sheer weight of bodies and it’s soon taken prisoner. Then the crew round up the goats to take them back to their ship for sacrifice. The Doctor protests, so Gammades knocks him unconscious, then he tells his crew that tonight their gods will get drunk on blood and tomorrow they’ll all be going home.

Later, the Doctor finds himself chained to the mast of the Gamma while the crew enjoy a party to celebrate their impending escape from the reef. He tries to convince Lucor to call off the sacrifice and let the Ruhk go, but to no avail. The Doctor wants to get the beacon back, but Lucor says it’s up on the surface with Eumachus and out of their reach. The Doctor suggests firing a net from the harpoon gun, but Lucor says he’s tried that already and it didn’t work. When Lucor returns to the party, Brewster sneaks over and releases the Doctor with keys stolen while the crew weren’t looking. The Doctor hurriedly starts priming the harpoon gun and sets it to stun. He hopes this will provide enough power to knock the geometer out of Eumachus’s grasp. All they have to do now is wait for Eumachus to come back into orbit above them.

As the Ruhks surround the Gamma, the crew take up defence positions and prepare to repel any that try to board the ship. Lucor says they’re easy targets and can be picked off one by one using the harpoon, but Nyssa thinks they’ve just come to rescue their friend and reminds Gammades that the creatures are blind and in pain because the dimensions here are too heavy for them. The Doctor says they’re simply being drawn to the geometer like moths to a flame and points out that firing at them might destabilise the entire reef. Then suddenly something seems to scare the Ruhks and they move apart. The crew are surprised to see Lady Vuyoki walking straight through the creatures like Moses parting the Red Sea. Gammades orders the doors to be opened to allow her entry, but the Doctor is intrigued that the Ruhks seem terrified of her and can’t get out of the way fast enough. He warns Gammades not to let her aboard and insists they talk to her first to find out what she wants, but the Commander overrules him and Lucor opens the doors. The Doctor tells Nyssa and Brewster to go down to the hold and release the captured Ruhk while he goes to pay his respects to Lady Vuyoki.

Gammades urges Vuyoki to hurry but she refuses to come aboard until he tells her whether “he” is here. The Commander thinks she’s referring to the Ruhk they caught, but she says she means Old Birth. The Doctor arrives and when Vuyoki spots him she immediately rushes on board. Gammades congratulates her on her courage and offers her the use of his own personal cabin, but then suddenly the entire ship is jolted by an earth tremor. The Doctor warns them the dimensional bubble can’t be sustained for much longer, but Vuyoki believes she’s being tested and that her final trial was to seek him out. She tells him she’s renounced her home and walked through the forces of darkness to reach him, so now she’s ready to be led to her new life. The Doctor assures her he’s not who she thinks he is and, despite her every denial, he also points out that she’s very much alive.

Nyssa and Brewster descend to the hold and find themselves in a charnel house, surrounded by the bloodied remains of the sacrificial goats. They soon locate the captured Ruhk and Nyssa says they must free him at once, but the nets are made of spun metal and Brewster can’t cut through them.

Lucor reports that the Ruhks are crawling closer all the time, but Gammades laughs as he’s looking forward to battle and he regards them as nothing more than future sacrifices. The Doctor joins them and points out that the world is shrinking and no amount of sacrifice will help them. The Doctor starts collecting together all the items stolen from his TARDIS, including the fault locator and the power lens unit. Gammades sends orders for Lady Vuyoki to join him for one last meal, but when the message comes back that she’s refusing to come as she has food of her own, the Doctor realises this answers his question about the missing food machine too!

Unable to release the captured Ruhk, Nyssa and Brewster race out of the hold as the earth starts to shake. As they move through the ship, they hear someone crying and eventually track it down to Lady Vuyoki, who’s devastated that the Doctor told he she isn’t dead.

Commander Gammades reminds his crew that every dead Ruhk is a potential sacrifice to their gods and he offers a reward to the man who kill the most. Every stand they make may be their last, so he tells them they should make it count. A call comes through that the creatures have made it to the ship, so he formally declares war and orders Captain Lucor to lower the force shields to let the Ruhk in…

Brewster can hear the commotion on the deck and tells Nyssa the battle has started. Vuyoki is upset that she’s no longer the centre of attention and asks them if they want to know how she died. She explains that each year, at the dead of harvest, a tribute flies in thanks to Maribu, their Sun. She was his chosen bride, packed away in her bridal urn on a ceremonial starship with 50 jars of grain. Brewster thinks it sounds more like she was a sacrifice, but she believes she was being sent off to marry. Unfortunately there was some sort of storm and she crashed here instead, dead and beset by monsters. She’s been waiting here ever since for the messenger of Old Birth to lead her from the afterdeath to her next life, and the only person who’s ever shown her any kindness in all that time was Brewster who gave her his food machine. The Doctor arrives just in time to hear how generous Brewster was with his equipment and wonders how much he charged her for the gift. Brewster says he gave it to her for nothing, but the Doctor knows he also made a tidy profit from the jewels he offered her at the same time. He becomes increasingly hostile and Brewster tells him to stop having a go at Vuyoki as it wasn’t her fault. The sound of battle gets louder and the Doctor says Gammades is a fool for thinking he can beat the Ruhks. Now that they’ve all cleared the air, they decide to intervene before both sides wipe each other out, but Vuyoki asks Brewster to stay behind as she’s sure she can think of some tasks he can do for her…

On the deck, Gammades and Lucor are enjoying the battle as they’d almost forgotten what it was like to fight. One of the huge Ruhks lands before them and demands to know where their brother is, but Gammades swears he’s out of their reach. He lunges towards the creature, but the bird flies away before he can reach it. Gammades orders Lucor to put the force shield back up so they can have a break, but just then the whole reef starts to crack, freeing the ship up. Lucor contacts the crewman Phyton in the engine room and tells him to stoke up the furnaces immediately.

In her room aboard the Gamma, Vuyoki is enjoying a foot massage from Brewster. Suddenly a huge Ruhk appears at the porthole and smashes through the glass in an attempt to reach her. Brewster tries vainly to force the creature back out, but then Gammades appears and kills it. Brewster is curious that Vuyoki seems terrified of the Ruhk, yet earlier she walked calmly through entire ranks of them. She complains about being haunted even after death, but Gammades assures her she’s not dead and points out that she has a heart beating fast in her breast. He promises to protect her and says they’ll soon be away from here. He wants her to start a new life with him and she sees him for the first time as a genuine hero. As they embrace, an embarrassed Brewster makes an excuse to leave…

Nyssa takes the Doctor down to the hold where he tries to release the captured Ruhk. Unfortunately he’ll need a diamond laser to cut through the nets and he can’t imagine Gammades will be willing to lend them one. Nyssa says she tries to find the good in everyone, but even she is being challenged by Lady Vuyoki. At the mention of her name, the Ruhk says his people fear her as her heart is pure with dark. Nyssa wonders what’ll happen when they release the Ruhk and the creature tells her they’ll fly unbound, back to the everness beyond the passages to time. These are pan-dimensional places the Doctor says he’ll probably never go to. As Brewster joins them, they hear the engines of the ship engaging and the Doctor is concerned it’ll tear the reef apart. Unfortunately Brewster allows the door to the hold slam behind him - and as there’s no handle on this side, they‘re now trapped. Suddenly there’s another tremor…

Captain Lucor orders more power from the engines in the hope of shaking the remaining Ruhks off the ship. The engineer warns that they may tear the Gamma apart and suggests powering down, but Lucor ignores him. Then the engines shut off completely and Lucor is resigned to the fact that they’ll never get away now. Commander Gammades arrives just in time to hear him and reminds him he was once a hero who’d never surrender. Lucor admits that he’s getting old and sometimes he just wants to go home to his pension. Phyton reports they can try again shortly after he patches up some of the damage, so Gammades orders all crew to the deck and tells them to bring the captured Ruhk with them. It’s time for another sacrifice to their gods!

Brewster tries his best to break down the door to the hold, but eventually he has to accept there’s nothing he can do. The Doctor realises that if the ship does break free, they’ll never reach the TARDIS again. Brewster reminds him the ship’s dead anyway, but Nyssa says if they can reach the geometer, there’s still a chance. The caged Ruhk points out a hatchway above them that they hadn’t noticed. They can’t reach it as it‘s too high, but the Ruhk says it will soon come to them. To their amazement, the floor itself starts to rise and the hatchway opens…

…to reveal that they were standing on a platform that can rise and fall to allow the Gamma to take on board cargo. They find themselves on the deck, surrounded by Gammades and the rest of the crew, together with Lady Vuyoki. The Doctor calls out to them to stop this tragedy, but Brewster is more concerned about the sky which appears to be falling rapidly. The Doctor says the dimensional field must be at its limit and the geometer can’t sustain it any longer. Lightning bolts flash across the surface as Gammades steps forward to begin the sacrifice. Nyssa pleads with him and says the Ruhk has done them no harm and the Doctor says the death of Eumachus must have been an accident as the creature was lost and confused. He also points out that a true sacrifice means giving up something you depend on, not just the murder of a bystander. From his pocket he produces the energy lens from the TARDIS and says it can focus the power of the Gamma’s neutron engines to help them get away. Although it never worked for them before, that was simply because they didn’t know how to operate it properly to make it compatible with their systems. He hands it over to Lucor, but Nyssa is worried as she knows they need it for the TARDIS. The Doctor argues that the Ruhk is more important than his ship, but Gammades is still intent on making an offering.

Lucor gives the energy lens to the engineer and passes on the Doctor’s instructions how to use it. Phyton is sceptical, but does as he’s told - and the effect is instantaneous.

Gammades tells the Doctor that his sons need a new mother. He’s sworn to lead Lady Vuyoki to her new life and the sacrifice of the Ruhk will bless their union. The Doctor is shocked and asks Gammades whether he read the inscription on Vuyoki’s funeral urn? The hieroglyphs roughly translate as “Maribu, Great Star, take into your fiery heart this lost soul by whose murderous hand 2,000 slaves met their deaths. Cleanser of the wickedness for which we on this world have no remedy”. Brewster remembers that Vuyoki claimed to be the bride of the Sun, but Nyssa says she was lying. Vuyoki becomes hostile and describes her victims as giggling hyenas. She made them all pay after they laughed at her when she tripped and fell on the palace steps. Gammades supports her and tells her not to worry as they were only slaves, but Vuyoki regards everyone - including the Commander - as her slaves. The Doctor believes they both deserve each other. Gammades offers him free passage on the ship, but the Doctor says he’d rather return to his dead TARDIS.

Eumachus appears on the horizon again, still clutching the Doctor’s conceptual geometer. While they’re distracted, Brewster snatches the controls of the net containing the Ruhk and tries to release the creature, but Gammades grabs hold of him. Vuyoki implores him to crush Brewster, but the boy throws the controls to Nyssa who uses it to unlock the bolts holding the net to the platform. The Ruhk flies up into the air and Gammades challenges it to a fight. He draws his sword and prepares to go back to the glory days of his youth. The Ruhk tells his friends to go home, but Gammades withdraws the gangplank that leads down to the reef. Nyssa says the entire place is in meltdown, but the Doctor says they have to get away before the ship leaves. The engines of the Gamma power up, so the Doctor, Nyssa and Brewster leap overboard…

They land safely on the rock below, but the dimensions are now shifting so much it’s hard for them to focus. The Doctor grabs their hands and leads them away, but then they see the most beautiful creature flying above them. The Doctor explains that this is the true pan-dimensional form of the Ruhk. The creature asks if the Doctor is ready, then the Doctor drops down from the reef and disappears from sight. The Ruhk tells Nyssa and Brewster not to worry as he’s gone to find the geometer and they’ll be going home soon…

The Doctor, carried through the air in the claws of one of the Ruhks, is amazed by the view of the reef as it dissolves beneath him. He sees the Gamma breaking free and leaving, but then his attention is taken by Eumachus who appears beside him, still calling his greeting to his crew even though they’re no longer below. The Ruhk tells the Doctor to take his equipment and he snatches the geometer from Eumachus’s grasp.

The Ruhk lands back on the reef and presents the geometer to Nyssa and Brewster who are waiting by the TARDIS. There’s no sign of the Doctor and the rocks beneath their feet are crumbling rapidly. Then Brewster spots the Doctor flying towards them. The Ruhk gently lowers him to the ground and then admonishes him, telling him to be more thoughtful next time. The Doctor opens the TARDIS and tells his companions they need to get the geometer installed inside. Brewster peers through the door and says there’s nothing but darkness, but as the Doctor points to a tiny grey cluster formed from all that’s left of the TARDIS interior, crushed into a single knot. Somehow they have to link the geometer to that knot so it can unravel the dimensions. The problem is they can’t reach it and the reef is rapidly breaking up.

Brewster takes the geometer and prepares to jump into the darkness, but the Doctor warns him he’ll be annihilated. Ignoring the advice, Brewster leaps through the door and disappears completely from sight. The Doctor mourns another wasteful sacrifice, but then he and Nyssa watch in amazement as the TARDIS starts to open up like a flower. The spatial dimensions extrapolate and initiate, then the temporal drive is installed, followed by the astral navigator and the memory banks. Slowly, bit by bit the entire interior of the ship becomes activate and the internal architectural is reinstated.

The Doctor and Nyssa enter the control room and find the TARDIS has been restored to normal - but at what cost? Suddenly the Ruhk appears beside them. It survived the battle with Gammades because his weapons were unable to harm it once the dimensions coalesced. The Doctor is glad that at least something survived, but the Ruhk says the Commander’s ship is also safe. It also found something else lost in the void - and, to Nyssa’s delight, Brewster reappears, apparently unharmed. The Ruhk asks the Doctor to take more care of him in the future, then the creature disappears back to its own dimension. Nyssa points out that they no longer have an energy lens and the Doctor agrees that its loss is going to be a problem. Brewster is surprised as he saw a whole box of them earlier in a downstairs cupboard. The Doctor claims he always knew he wasn’t giving away the only one, but his voice suggests he may not be telling the whole truth. Brewster goes to fetch one and Nyssa asks the Doctor what happened to the Gamma.

Connie Winter returns home from another routine day at work and complains that her flatmate Taz hasn’t bothered to pick up the post, even thought she’s evidently gone through it and established that it’s mainly bills. She offers to make Taz a cup of tea, but they’re out of milk. She wonders what Taz has been doing all day, then she apologises for being a bit bad tempered and says she’s had the day from hell. They announced at work that her department was being closed, then the Jubilee Line was like “Dawn of the Dead”, so the least she expected was that her flatmate might have got in some milk while she was supposedly out looking for a job. Taz is waiting for a dieting programme to start on TV (just in case she feels like going on a diet later) but in the meantime she’s been watching the News - which seems to be all bad as usual.

Taz tells Connie she needs to get a plumber in as there’s a problem with the bath, then she remembers that someone rang earlier about missing rent, but she switched the answer phone on after that so she doesn’t know if anyone else called. Connie checks the messages - the first is from her mother calling to say that she’s had another argument with her father, then the second is from Connie’s boyfriend Richard cancelling his plans to see her tonight.

Connie decides to get some fresh air, but in her depression she walks out into the road and nearly gets knocked down by a taxi. She thinks to herself how nice it would be if, just for once, something in her life didn’t turn out to be total rubbish. She finds herself on Southwark Bridge and as she looks down into the Thames, she’s approached by a young man who asks if she’s alright. She assumes he’s begging for money and tells him she‘d rather be alone, but he says he was worried she was going to jump. He tells her he used to live around here and worked on the banks of the Thames for a man called Mr Creek. Connie is sceptical as his story sounds like something from the musical “Oliver!”, especially when he talks about the place being full of fog and horses. Connie is freezing, so against her better judgement, she invites the young man for a coffee.

In a nearby late-night café, Connie tells the young man how miserable her life is at the moment. Even the news seems to be full of stories about wars that shouldn’t be happening and the polar ice caps melting. She can’t help feeling things are getting worse. The man asks her how she’d feel if she was visiting from 100 years ago and she gets the distinct impression he’s talking about himself. He thinks it would be paradise - there’s so much food, everyone’s healthy, there are machines that can take you anywhere you want to go and best of all, men have stopped going around with big bushy beards. She agrees, but says it doesn’t make facing tomorrow any easier. She’s enjoyed talking to him as it makes a change from her ex-boyfriend Richard who never wanted to do anything that wasn’t all about him.

After their coffee they go for a stroll and Connie asks the man where he’s from. He says he came from the workhouse in the London of 1867, and although she doesn’t believe him she can tell he really means it. He explains that he came here in a time machine and points to the blue police box on the other side of the road. He says he’s seen a different version of 2008 where things went wrong, so even thought this isn’t a perfect world, she should be happy. He doesn’t think anyone would want to live in a perfect world anyway, but Connie says she would. He asks when he can see her next so she writes down her address and warns him about her extremely large flatmate. As they head off in different directions, she calls out and asks what his name is and he tells her it’s Thomas Brewster. She then watches in amazement as Brewster enters the police box and it disappears before her very eyes!

Elsewhere, two engineers, Phil and Trev, argue over whether the girl’s words qualify as a call out. Phil believes it’s an Emergency Code 9, which means under the regulations they don’t have any choice. Trev reluctantly agrees, so they activate their equipment and set the process in motion…

The TARDIS materialises and the Doctor says they’re on Earth in London, 2008, as requested by Brewster. Apparently he wants to know what the future should be like because all he’s seen of 2008 so far is a smouldering desolation from an alternative Universe! Nyssa fetches him and the three of them go outside to find they’ve landed back in the Doctor’s old study in Baker Street. The place clearly hasn’t been occupied in over 141 years and from the amount of dust the Doctor guesses he must have forgotten to pay the cleaner. Even the furniture, which was new when he bought it, now consists of genuine antiques held together only by cobwebs. The Doctor explains that he gave his solicitor strict instructions not to sell or let the property and he still has the title deed somewhere.

They go out into Baker Street, which looks completely different from the last time they were here. Brewster remembers where the underground station is, so he tells the Doctor and Nyssa there’s someone he has to see and dashes off before they can stop him. Nyssa is baffled by his actions, but the Doctor realises this means Brewster has been here before!

Connie is woken up by her alarm clock, then there’s a knock on her bedroom door. Her flatmate Taz enters with a tray, claiming that it’s her turn to bring her an early morning cup of tea. They were supposed to be out of milk, but Taz says she picked some up yesterday on the way back from work where she‘s a management consultant. Connie is surprised but Taz (who now prefers to be called Tasmin) says she didn’t spend three years at University just to sit around all day. Tasmin opens the curtains and Connie is amazed to see how slim her flatmate is, but her friend says all the credit is down to her personal trainer. Connie thinks she must be dreaming as this doesn’t sound like the Taz she knows. Tasmin asks how her evening with Richard went and compliments her friend on her choice of a perfect boyfriend. Connie says they’ve split up, but Tasmin knows Richard proposed last night and thinks it’s odd she doesn’t remember…

The Doctor blames himself for not guessing earlier that Brewster had been here before. Not only did the boy ask to come here, he even specified the exact date. When Brewster saw the traffic he should’ve been amazed, bewildered or even terrified - but he accepted it much too easily because he’d obviously seen it before. It must have happened when he was travelling alone aboard the stolen TARDIS. Suddenly the Doctor becomes aware of something strange. This is the early morning rush hour and the traffic should be at a virtual standstill, but it’s moving quite smoothly. Something is obviously very wrong here…

Connie thinks the bathroom in the flat looks like a hotel and asks Tasmin if she’s been tidying up, but her friend says no more than usual. Connie is relieved to discover she still works for the same company - at Rothery House - as it means she’s not going completely mad. She tries the answer phone and there’s a message from her mother saying she’s been invited on a surprise mini-break by her father to celebrate their anniversary. Now deeply worried, Connie switches on the TV and watches the News, but this time everything that was bad yesterday has now been turned around and there’s nothing but good news! She asks Tasmin if she took a call yesterday about missing rent, but her friend says she didn’t. Tasmin asks if something’s wrong, but Connie says it’s quite the opposite.

The Doctor buys a copy of The Times and asks Nyssa to comment on the headlines. She browses through them and notes that everything seems normal, but he wants to know what’s happened to all the political scandals, the disasters and the binge-drinking celebrities? He points out that all the news is good - including a fantastic cricket result for England - which proves what he was beginning to suspect. All the people around them seem perfectly happy and healthy. This isn’t the Earth that they know - humanity has been changed for the better and the whole world seems to have been improved. Nyssa wonders if Brewster did something during his travels, but the Doctor can’t believe an alteration in the time stream would have such universally benign consequences. However, he agrees that whatever’s happened, Brewster must be at the heart of it.

Brewster arrives at the address Connie gave him and knocks on the door. Connie answers, but she doesn’t seem particularly happy to see him. He reminds her that they’d agreed to meet up again after their encounter last night, but she doesn’t have a clue what he’s talking about. She says she doesn’t know him, nor does she want to. He mentions that she’d told him she’d split up from her boyfriend, but she insists they’re very happy together and have just got engaged. Frostily, she pushes past him and heads off for work.

Connie arrives at Rothery House Publishing and immediately notices how tidy everything is. She tells her friend Sophie she’s had the most amazing journey to work as every train was on time and she even got a seat, but Sophie doesn’t think that sounds particularly unusual. Connie asks what’s happened here as half the staff are different and Sophie seems to be working instead of reading celebrity magazines while scoffing a box of éclairs. Sophie laughs at such a ridiculous notion, which freaks Connie out, but worse is to come as Sophie reveals that Connie has her own personal office and that she runs the whole company.

The Doctor hurries Nyssa back to the TARDIS. If there’s been any extra-terrestrial interference, the Doctor hopes he can locate the source. Before they can enter, Brewster arrives and rushes to join them. As the accusations fly, he promises to answer all their questions, but first there’s something he has to tell them that they’re not going to believe…

At Rothery House Publishing, Connie has an unexpected visitor - an exact duplicate of herself. The new arrival demands to know who Connie is and what she’s doing in her office! Connie is shocked, not least because her own clothes look better on the new Connie. She realises they must both be the same person, but she tries to convince the other person that she shouldn’t really be here, but the new Connie suggests that perhaps its she who shouldn’t be here. The new Connie says she’s never made a single mistake in her entire life, so Connie challenges her and says that when she was 16 she got drunk at Nathan Green’s birthday party and snogged Sean Clarke’s brother. The new Connie didn’t do that and, in fact, she only ever drinks alcohol in moderation. During her French A Level, Connie got so nervous she threw up over her invigilator, but the new Connie passed with an ’A’. Connie missed the Kaiser Chiefs concert in 2004 because she went to the wrong Newcastle, but the new Connie can’t believe anyone could make such a mistake. It’s clear that the new Connie is an alternative version who never got anything wrong. She’s perfect. In fact, everybody here is perfect, except for the original Connie. Horrified, she thinks everyone must all have been taken over, so she leaves before they can get their hands on her.

Brewster tells the Doctor about the girl he met and says she’s been substituted or changed and the new version was unfriendly and full of herself. The Doctor asks him to run through everything he did and everyone he spoke to the last time he was here, but the only person Brewster met was Connie. The Doctor checks the controls and discovers Brewster never materialised the TARDIS properly and created a quantum fissure in the fabric of space-time. Connie must be the focal nexus so they have to find her before the wave function collapses. If she’s part of what caused this, the real Connie should still be out there. Brewster has already tried her flat so the Doctor urges him to think of any other place she could be…

The TARDIS materialises on Southwark Bridge where Brewster first met Connie. He sees her and is relieved to discover that this version still remembers their meeting which, for her, was only last night. The Doctor and Nyssa introduce themselves and explain that something is affecting the planet. Connie says she’s already noticed and says she met herself at work today and although the other version was better looking and had a really great career, she was also really annoying. The Doctor thinks that whatever’s happened, it was done for her. They invite her into the TARDIS to explain further. Connie is amazed by the TARDIS interior and realises Brewster was telling her the truth. The Doctor tries to establish the source of the quantum disruption and discovers two lifeforms have broken through the space-time fissure. Suddenly two men appear in the control room and dump their bag of tools on the floor. They explain that they’re here because they got a call out for an emergency repair. They play back a recording of Connie and Brewster speaking last night in which Connie said she’d like to live in a perfect world. Her words came through on the sub-ether, a fissure opened up and they arrived to do an urgent patch-up job. They say it was a textbook case and it only needed a bit of tweaking around the focal nexus.

Phil and Trev introduce themselves as existential maintenance workers - they repair reality and no job is too large for them. Connie is surprised they took her words so literally and says she doesn’t really want to live in a perfect world. Yes, it would be nice if things were better, but for that to happen people need to make themselves better. A perfect world would be boring as you’d never have anything to moan about. The Doctor agrees and says life doesn’t come with satisfaction guaranteed - if you take away the opportunity to get things wrong, you take away the reasons for getting things right. Being human is all about the mistakes, the imperfections and the failures. Burning your toast, losing your keys and getting off at the wrong stop are the sort of small pointless blunders that life is all about. Phil and Trev realise they’ve made a mistake and start blaming each other, but Nyssa says the only important thing is whether they can put things back to how they were. Phil and Trev know Connie isn’t satisfied, but they ask Brewster what he wants to happen next as it was a joint request. Brewster isn’t sure what to say and asks the Doctor for help, but the Doctor says only he can choose what path to take.

Connie and Brewster leave the TARDIS. He’s decided not to continue travelling with the Doctor and Nyssa any more as it’s real life that matters. He thinks staying with them would mean running away. He’s always been shoved around from place to place by other people, but he’s never found anywhere he really wanted to be until now. This place might not be perfect, but it has a few things going for it. He’s met two versions of Connie today - a perfect one who was a bit scary and a real one who’s funny and keeps laughing even when she gets upset with the world. He wants to be with the real one, but Connie warns him they hardly know each other and things might not work out. She says her life is a total mess - she’s at risk of losing her job, she’s late with her rent and her parents are lunatics. He says he knows that, but that’s half the fun and he can’t think of anywhere he‘d rather be. They kiss and she invites him back home to make some mistakes together. Just then her phone rings and her mother tells her she’s thrown her husband’s clothes on the lawn and set fire to them. Connie thinks that’s wonderful…