As he patrols the parapets at the top of the Citadel of Peladon, the guard Frankis freezes to the spot when an ethereal female voice whispers to him from the shadows. At first he thinks it must be someone playing a joke on him, but when the voice warns that Peladon will soon bathe in oceans of blood, he becomes genuinely afraid. He asks who the voice belongs to, but she replies simply “Death”. King Pelleas arrives and asks why the guard isn’t joining the others for the celebrations and Frankis tells him he’s on duty until midnight. Pelleas says midnight is the witching hour and it’s the time when the ancients of Peladon are said to have pledged their souls to the Dark Beast in exchange for power and immortality. Pelleas plans to take a turn around the battlements and maybe even climb the old bell tower. After all, it’s not every day one becomes King. Frankis tells him his mother would have been proud of him, but then apologises for raising the subject.

After Pelleas leaves, Frankis‘s colleague Nardo arrives and mocks him for mentioning the King’s mother - if she hadn’t done away with religion before she died, Pelleas would probably have made Queen Elspera a saint by now. Frankis rebukes Nardo for being late and Nardo wonders if he was getting frightened on his own as the spirit of Elspera is said to walk these very battlements when the moon is full, clamouring for her murder to be avenged. Frankis insists that her death was an accident, but Nardo points out that no one ever found her body and he believes the old Queen Mother did away with her as they never saw eye to eye. Frankis remembers the voice and asks Nardo if he’s ever seen or heard anything funny during his watch, but Nardo changes the subject and offers his colleague a bottle of firewater.

Pelleas wanders through the battlements and as soon as he’s sure he’s alone, he calls out to his mother. The ghostly voice greets Pelleas and the King is overjoyed to discover the rumours that she’s returned as a ghost are true. The voice tells him she must soon return to the sulphurous flames from whence she has come, but she tells him that if ever he loved her, he must avenge her murder. She says the stories that she died hunting in the forest, after being unseated and falling to her death, are lies. She says she was murdered by someone not of this planet, and that offworlder is approaching Peladon again. When her killer arrives, Pelleas must kill them. The ghostly voice disappears, carried away on the wind.

Ambassador Zixlyr sends out a distress call, requesting urgent help. He says his spaceship has been attacked and the pilot is dead. He himself is wounded and the ship is haemorrhaging fuel from the rear engine. Shortly afterwards, the TARDIS materialises inside the ship and the Doctor, Erimem and Peri emerge to discover the damage is extensive and there are flames everywhere. The Doctor says this is reassuring as the existence of fire means the life support system is still working and is pumping oxygen around the ship. There’s still hope for the crew, but they need to find the bridge quickly.

Deep in the tunnels beneath Mount Megeshra, a very young miner is hard at work alone, digging for trisilicate away from the main group. His father, the foreman, tells him Elkin has taken some resonance soundings and believes they’ve already reached the end of the seam. The boy is sceptical and produces a very large lump of trisilicate which convinces him he’s working in the right area. The foreman is impressed and says he’s never seen anything this beautiful in his 37 years as a miner. The boy suggests they send Elkin back home to Vega Nexos so they can get a replacement who actually knows what he‘s talking about. The foreman tells his son he’s proud of him and reminds him not to be late home for tea. Once he’s alone, the young miner resumes digging and eventually breaks through into a hollow cavern, which proves that Elkin was right after all. Just then the ghostly female voice echoes round the caves. It tells the young miner that it’s thirsty and that it can smell his blood. It demands the miner give his life to her and the boy dies instantly, screaming out for his dad.

The Doctor, Peri and Erimem arrive at the bridge of the ship, but suddenly a wall of fire erupts in front of them, completely blocking their path. Peri finds a fire extinguisher and quickly puts out the flames, earning congratulations from the Doctor. He taps in a code on a panel next to the bulkhead and the wall slides back to reveal Ambassador Zixlyr.

In the cave system, Elkin secretly contacts his ally Arktos by radio and demands to know why he’s not been in touch for days. The Arcturan insists that he’s been busy and asks how things are progressing on Peladon. Elkin says they found the trisilicate mother lode a week ago, but ever since they started mining it, things have been going wrong. Machinery has gone haywire, there have been random cave-ins and some of the miners are even claiming to have heard voices. Arktos regards them as superstitious primitives and reveals that he’s on his way to Peladon right now and will be able to assess the situation first hand very shortly. Elkin warns him there’s a security net around the planet because of the forthcoming wedding, but Arktos has already gone. Just then, the foreman races into the cave and reports that there’s been a murder - and his own son was the victim!

Peri recognises the Ice Warriors from a previous encounter and tells Erimem that they come from Mars. The Doctor asks Zixlyr what happened and he says he was en route to take up his new post when the ship was attacked. Two fighters blasted their fuel tanks as they were passing close to the border of Arcturus and his pilot was killed. Suddenly there’s another explosion from a hull breach and the Doctor urges everyone to get back to the TARDIS before the ship disintegrates. Unfortunately the TARDIS was in the rear cargo bay and this was the section that just got blown away. The forward scanners reveal that the outside of the ship is on fire, which means they’ve already entered the atmosphere of a planet. The Doctor demands access to manual control and Zixlyr begins work on stabilising the shields. The ship is still coming in too fast so Zixlyr begins adjusting the gravitational buffers. The radar seems to show two images coming in on the same trajectory, but the Doctor assumes this is another section of their ship that’s broken away and is coming in on a parallel path. The only options available to them are to crash land on the mountains or in the forest, so the Doctor selects the latter. The ship’s force fields finally give up so the Doctor tells everyone to strap down and prepare for a crash landing…

Princess Pandora hears a ghostly voice in her sleep, telling her to expect to meet her destiny soon. She’s woken by a call from the Ambassador Alpha Centauri who says they’re about to land on the planet Peladon. By the time Pandora arrives at the airlock, the final security checks are being conducted and a royal escort has been dispatched. Alpha Centauri says Pandora looks every inch the new Queen of Peladon, but Pandora just hopes she lasts longer than the previous one! Centauri agrees that it was a most unfortunate hunting accident, and as it’s only been a week since his mother died King Pelleas is probably still in mourning. Pandora asks what Pelleas is like and Alpha Centauri says he’s very young but he should become as great a ruler as his beloved mother Queen Elspera. With Pandora at his side, galactic peace is certain and Peladon‘s place within the Federation is assured. Pandora adds that the arranged marriage will also give her father access to the trisilicate reserves. She’s never even met the boy she is to marry and she doesn’t know whether he’s kind or cruel, intelligent or stupid, or even sexy! As the airlock opens, Centauri gives the Princess one word of warning - to be careful of the old Queen Mother Beldonia as she’s opposed to the marriage and will do anything to prevent it taking place.

At that very moment, Beldonia is in the Temple of Aggedor. She confesses her sins and accepts that the secret she keeps from her grandson would destroy him, so she prays for the strength to hold onto it and the fortitude to face what is to come. As she seals her prayer with an offering of her own blood, she hears the ghostly ethereal voice calling out to her. But before she can react, the door opens and Pelleas enters to announce that Pandora has arrived. Beldonia insists that her grandson address his future wife by her formal title. Beldonia may not approve of Pandora’s background, but she should still be granted a modicum of formality. Pelleas is clearly nervous about meeting his future wife and wonders what she’ll be like, but Beldonia warns him that if he continues prattling like this in front of her, she’ll probably get straight back in her ship and head back home to Earth. Beldonia doesn’t approve of the wedding because she believes it represents Earth imperialism. Pelleas suspects that his grandmother simply doesn’t like offworlders, but as he says that, he’s suddenly reminded that the ghost of his mother told him her murderer was an offworlder who was returning to Peladon. His voice hardens and he prepares to go and meet Pandora.

The airlock to the crashed Martian spaceship is kicked open and Peri and Erimem emerge, coughing from the smoke inside the burning wreckage. They manage to carry the badly injured Doctor out, then Zixlyr follows with the medi-kit. He warns them to take cover and seconds later there’s an enormous explosion as the ship blows up and the four of them are thrown to the ground.

Pelleas asks his grandmother to think of Peladon and Earth united once again by a royal marriage. Beldonia reminds him that it was tried once before and it failed, and she suspects Earth only wants an alliance with their planet because they want their mineral riches. Pelleas argues that they have plenty to spare and Elkin has said he’s found a completely untapped seam that’s ten times as pure as the ordinary trisilicate. Beldonia is convinced that Peladon will be forced to become Earth’s colony and she says Pelleas sounds more like his naïve mother every day. He becomes angry and storms off, but before Beldonia can follow, her attention is distracted by the King’s Champion Grok who emerges into the corridor from a nearby secret passageway. He warns her of another death in the mines and says investigations are underway. He also says it’s time for the Hunt. She seems surprised as it’s only been a few days since the last one, but he tells her the Beast is already hungry. Beldonia is worried there won’t be anything left alive in the forest to hunt, but Grok says the Beast always finds something…

Near the crashed spaceship, Erimem has built a fire and is praying to Osiris for his aid in healing the Doctor when she‘s interrupted by a terrific howl coming from deep within the forest. The Doctor suddenly wakes up and wonders where he’s heard that sound before. Erimem tells him Peri and Zixlyr went off about an hour ago to get help, but the Doctor’s wounds are already repairing themselves. Although Erimem believes it’s a gift from the gods, he tells her it’s actually due to his Time Lord physiology. He says full-body regeneration is a costly process so ad hoc repairs are the norm. They hear the howling again and the Doctor searches his memories to see if he can place it.

Zixlyr asks Peri if she wants to stop for a rest, but adds that they still have a long way to climb. Peri takes offence when he addresses her as “girl” and he apologises. He explains that his own name translates as “twin of the ice” and Peri says hers means “she who lives in the hills”, which is ironic as she should be happy up here amongst all the boulders. She makes a joke about her step-father, then asks Zixlyr if he has any family, but he changes the subject and encourages her to continue their journey to the Citadel.

Awaiting the arrival of their honoured guests at the reception, King Pelleas asks Nardo where his grandmother is and he’s surprised to learn that the Queen Mother has chosen such a time to go hunting in the forest. The Royal Herald appears and introduces the congregation to the Ambassador Alpha Centauri and his charge Princess Pandora from Earth, soon to become the Bride of Peladon. The crowd cheers…

The Doctor and Erimem race through the forest, but it soon becomes clear they have no hope of outrunning the beast. The Doctor says their only chance is to find something shiny or sparkly like a watch or a jewel. Erimem offers him her signet ring and the creature is almost upon them when the Doctor begins singing "klokleda partha menin klatch, naroon, naroon, naroon". Within seconds the lullaby works and the terrifying beast calms down and even allows the Doctor to pat it gently like a favourite pet. He tells her that Aggedor is an old friend and he’s pleased to see that the creature seems to like Erimem too.

King Pelleas takes Pandora on a tour of the Citadel and eventually they arrive in the Temple of Aggedor. He explains about the Royal Beast and says his ancestors worshipped him as a god, but the people no longer believe such nonsense and his mother dissolved the church the moment she acceded to the throne. Pandora says she sounds like a sensible woman and adds that it’s a pity she didn’t dissolve arranged marriages too. Pelleas is lost for words and Pandora realises she’s being crass. Pelleas says he’d already guessed that she didn’t like him, but she points out that she barely knows him. What she dislikes is the fact that their lives have already been decided for them. Pelleas thanks her for being honest and says his mother always believed this was the finest quality someone could possess. Pandora likes the sound of his mother and Pelleas thinks she would have liked her too. The Princess changes the subject and asks if there are any Aggedors left, but Pelleas tells her the last one died nearly a century ago while saving the life of Queen Thalira. He offers to show her a portrait of Thalira, but unheard by anyone, the ghostly ethereal voice is delighted and invites the Princess to come closer…

The Doctor tells Erimem that he’s been to Peladon more than once before, but it’s puzzling because the last visit was a long time ago and Aggedor died. Suddenly Queen Mother Beldonia appears from the forest and tells him this is not the same creature he once knew. Beldonia is impressed by Erimem’s royal credentials and she knows the Doctor from the history books, although he’s much younger than they describe. She explains that this Aggedor is a female and is the original creature’s offspring. Her existence has been kept secret for 150 years until now. Beldonia summons Grok and tells him to take Aggedor back to the dungeons while she returns to the Citadel with the Doctor and Erimem via a short cut.

Pelleas takes Pandora to the Hall of Portraits, a corridor lined with pictures and statues of his royal ancestors. Pandora is particularly impressed by the imposing beard of Pelleas’s grandfather Paladin the Great, and Pelleas has been told he wailed for hours after being scratched by it during his naming ceremony. The two of them laugh warmly and Pandora starts to regret what she said back in the Temple. Pelleas tells her to forget it and says he’ll be satisfied with them just being friends. The guard Frankis arrives and announces they have more visitors from offworld. He says they crashed in a spaceship and have been taken to the infirmary. Pelleas apologises to Pandora and invites her to stay here and look at some more members of his family while he goes to attend to the matter. Once she’s alone, Pandora explores the corridor in search of Pelleas’s mother, but then a secret passage opens up of its own accord in front of her. Intrigued by the possibility that it might lead to Peladon’s secret treasury (or it might just be a lovers’ escape route or even a short cut to the lavatory) she goes through.

Elkin arrives at the agreed rendezvous point in the southern quarry, but there’s no sign of Arktos. After waiting for over an hour, he contacts his co-conspirator and demands to know where he is. Arktos taunts Elkin for not looking hard enough, then he activates a control and his invisible spaceship appears right in front of him. Elkin is amazed and Arktos tells him the technique is incredibly expensive, which is why he needs all the trisilicate they can carry. Arktos decides it’s finally time that Elkin put a face to his employer and says he’s coming out. As the ramp slowly starts to descend, Elkin agrees to himself that it’s finally time he saw the man he’s going to kill…

Zixlyr and Peri are recovering in the infirmary inside the Citadel. Peri wonders whether anyone has found the Doctor and Erimem yet because the guard they gave directions to didn’t seem particularly bright. She thinks all the stone arches and the uniformed guards make this place seem a bit Medieval and even the medical area looks more like a mortuary. She’s intrigued when Zixlyr confirms that Peladon has had its fair share of deaths in recent times and he tells her about Queen Elspera, among others. Alpha Centauri arrives outside in a fluster, but Nardo refuses to let him see the patients until the King himself has granted permission. Centauri thinks Nardo is acting intolerably and reminds him that he’s known him since he was still in swaddling clothes. He orders the guard aside and is greeted warmly by fellow Ambassador Zixlyr - and Peri is amazed when Centauri addresses him as a Prince! Centauri doesn’t seem surprised when he learns Zixlyr’s ship was struck by Arcturan fighters and says there have been other incidents recently, but he refuses to go into details while Peri is present. Peri is worried they haven’t heard from the Doctor and Erimem since they left the crash site, but her words shock Centauri. With the Doctor involved, things could be a lot more serious than anyone thought, so he rushes off to find the King…

As they make their way up Mount Megeshra, Queen Mother Beldonia tells the Doctor and Erimem that she’s looked after her grandson Pelleas herself since his mother’s accident. She thinks he’s well-meaning but hopelessly idealistic. The Doctor points out that this is better than being cynical and hidebound, and Beldonia says she hopes he’s not referring to her in that way. They reach the top of a small peak and Erimem sees the Citadel for the first time and is impressed. Beldonia says her ancestors carved it out of the living rock more than a thousand years ago. Erimem is reminded of Castle Dracula.

Arktos presents himself to Elkin and notes that the engineer isn’t surprised by his appearance. Elkin has never met anyone from Arcturus before, but he’s read about his race and recognises the atmospheric pressure unit. Arktos interrupts him and demands to know more about the trisilicate. Elkin says all the mining has ceased for the moment because a young miner was found dead this morning and his body had been totally drained of blood.

The ghostly voice beckons Pandora further and further into the tunnels beneath the Citadel. She begins to wish she’d brought a ball of string with her and realises she must have been mad to be lured into the darkness like this, but the voice promises her a reward.

Peri is becoming impatient as the King still hasn’t come to talk to them yet. Zixlyr suspects he may have been waylaid by Alpha Centauri or perhaps he just has higher things on his mind. He crosses over to Nardo to see if he can find out more, but then he asks if he can have a word in private and the two of them leave the room. Peri’s impatience then turns to boredom - until she hears a struggle coming from the other room, followed by a groan. She calls to Zixlyr, but gets no response. Nervously she opens the door and finds Nardo unconscious on the floor. She can’t wake him up so she decides to go investigating…

Alpha Centauri apologises to Pelleas for inconveniencing him with his suspicions, but the King believes he’s acted wisely. It may be nothing more than diplomatic coincidence, but he agrees to have the person watched. He’s also intrigued that the Doctor appears to have returned after all these years. Although Centauri says he’s always been a friend to Peladon, he regards the Doctor’s arrival as an ill omen. History has shown that death travels with the Doctor and Pelleas feels they’ve already had their share of misfortune of late. He lists all the recent deaths, but leaves out the first incident as no body has been found and it may still be nothing more than a mysterious disappearance. Centauri says he hopes Zixlyr can appreciate the difference. Pelleas leaves to return to Pandora and Centauri takes the opportunity to report to his ally. The Arcturan voice on the end of the communicator asks whether he’s made contact yet and Centauri says he hasn’t although he believes the person they’re waiting for has now arrived on Peladon. The voice says it would prefer the person to be taken alive, but if he should resist the arrest, Centauri may have to kill him.

Beldonia leads the Doctor and Erimem to a huge door at the foot of the Citadel. She knocks for attention and the Doctor quotes from Walter de la Mare’s “The Listeners”, which makes Erimem wonder whether he has a quotation handy for every possible occasion. The door opens and the Doctor just happens to have an appropriate quote from “Henry V”…

Pandora eventually arrives at a door with a cat motif embossed on it. The voice says this is the Lioness, scourge of the desert, devourer of the weak and queen of all she surveys. Just then, Pandora hears Pelleas’s voice calling out to her. She decides to return to the Hall of Portraits, but the voice warns her that they’ll meet again and when they do, Pandora will face the Lioness herself…

Pandora rejoins Pelleas and asks her what she was doing down there. She apologises and says she was exploring and he says she’ll like it here because the Citadel is full of secret passageways. He used to have endless fun as a child hiding and leaping out unexpectedly on various aunts. She asks about the patients in the infirmary and he says he thinks they’re fine but he got interrupted en route by Alpha Centauri. They laugh again and then Pelleas decides to tell her the truth about what he experienced last night on the battlements. However, he’s prevented again by the return of Frankis with yet more news. The guard tells him Queen Mother Beldonia has returned from her hunting trip with two more offworlders!

The foreman tells Elkin that none of his miners will resume work until the mystery of his son’s death has been sorted out. Elkin claims to be sympathetic to the man’s loss, but says they’ve already fallen far behind schedule. The foreman grabs him and tells him he’s only concerned about the fat bonus he’s going to get at the end of this, but the miners know there’s something evil in the tunnels and he’ll see Elkin in hell before he risks losing anyone else. After the man leaves, Elkin receives a call from Arktos. The Arcturan tells him to arrange for the miners to assemble in front of the main seam at sunset this evening as he has a little surprise for them. Elkin asks him what he’s got planned, but Arktos simply says that it’ll be a very explosive revelation and he recommends that Elkin make sure he‘s somewhere else at the time. Arktos switches off his communicator and mumbles to himself that Elkin’s time is approaching too…

In the Ambassador’s quarters in the Citadel, Zixlyr searches desperately through a casket and removes an expensive looking necklace. At last now he can find out the truth about Alyxlyr. Peri emerges from behind the door and catches him red-handed. She brands him as a jewel thief and he accuses her of following him. She admits that her curiosity was peaked somewhat when he knocked out the guard back at the infirmary. She says she hopes he can explain his behaviour, but just in case he can’t she warns him she has a very strong pair of lungs. He tells her the object he found isn’t a necklace but a memory harp that belonged to the previous Martian Ambassador on Peladon. If he’s correct, it should contain information about why Ambassador Alyxlyr disappeared without trace nearly a month ago. He activates it and they listen to her final report. The voice of Alyxlyr announces that she fears she has been discovered. She says there is a dark secret at the heart of Peladon that kills. She believes Queen Elspera knows of it and perhaps even Pelleas too, although she hopes and prays that she‘s wrong. She goes on to say that she’ll activate the homing signal within the necklace in case this is the last message she’s able to send. She warns whoever may be listening not to trust the royal family here. Then her message ends. Zixlyr is furious and says this is all the evidence he needs. He’s convinced Alyxlyr must be dead and he says the royal family will soon follow suit.

The Doctor arrives in the throne room and notes that sometime in the last century it’s been re-decorated. It used to be all dark and gloomy, but now it’s bright, modern an utterly soulless. Queen Mother Beldonia agrees totally and says it was one of Elspera’s many ideas. She didn’t see eye to eye with the Queen on most things, but the people of Peladon loved her as she was beautiful, graceful and a reformer. The Doctor asks how she died and Beldonia says it was an accident and she was killed outright when she fell from her mount while out hunting in the forest. When she says no one witnessed the tragedy, the Doctor asks how she can be so sure of her facts, but before she can answer, King Pelleas arrives with Pandora. Beldonia greets the Princess but then makes a number of thinly veiled criticisms about her before introducing her grandson to the new arrivals. She particularly emphasises Erimem’s noble royal background and hopes Pandora will take note. Pelleas tells them they’re not the only offworlders to arrive at the Citadel today and he offers to take them to see Peri and Zixlyr. The Doctor chooses to remain behind to discuss some matters with Beldonia, but the Queen Mother claims to have prior plans and leaves to meet with Grok. After she’s gone, Pelleas apologises to Pandora for Beldonia’s rudeness and says she’s not normally so blatant. Pandora says she’s done enough walking for one day, so while Pelleas takes Erimem to see Peri in the infirmary, she decides to stay behind with the Doctor. Once they’re alone, the Doctor comments on Pandora’s rare name and she admits that she’s always lived up to it. Even as a child she used to poke her nose into things that don’t concern her. Realising the Doctor has been to this planet before, Pandora asks him a really strange question - are there any lions on Peladon?

Beldonia prays again to Aggedor and says that a dark malignancy is at work in the Citadel and she’s powerless to halt its advance. Death is everywhere and she wonders whether the visitors from the stars have brought this malevolence with them? She reveals that the Doctor has returned to help them and asks if he can be trusted - but the ghostly female voice speaks back to her and claims that the Doctor is their enemy and he must die!

Erimem is impressed by Pelleas’s guided tour of the Citadel but he’s surprised she doesn’t find all the stonework oppressive. She explains that she was brought up amongst sandstone and marble and she finds this place comforting. She believes Pandora is very lucky to be marrying someone like him who is intelligent, handsome and who cares for the lives of others. As they turn a corner, they find Nardo unconscious on the floor outside the infirmary and the Ambassador and Erimem are missing. Pelleas revives Nardo and orders him to arrange an immediate search - but then Pelleas suddenly hears the ghostly voice inside his head again, demanding to be fed with fresh blood. He cries out in pain and assures Erimem that it’s just a headache. He asks her to accompany him to the battlements to get some fresh air.

Peri dodges Zixlyr’s repeated attacks and the sword smashes into the wall, narrowly missing her head. He warns her she is only delaying the inevitable and says she should face her death with dignity. Peri asks what right he has to lecture her on dignity and tells him to start acting like a Prince. She says she accepts that if his sister was killed by Pelleas and Beldonia then he will want revenge, but she asks him to think about the practicalities. Zixlyr tells her the matter is already taken care of - the equipment he retrieved from the crashed ship wasn’t a medi-kit but a Xanthoid Volatiser. Then he launches in for another attack…

Beldonia’s prayers are interrupted by the arrival of the Doctor and Pandora, who apologise for bursting in without knocking. The Doctor asks the Queen Mother if she’s ever heard voices and although she dismisses it as a ridiculous question, he notes that she doesn’t actually deny it. Pandora admits that she’s heard it too, a low and whispering female voice. Beldonia rebukes her and says such madness is blissfully rare on Peladon and she dismisses the Princess as nothing more than a spoiled little brat from an upstart royal family with more money than sense. The Doctor intervenes and demands that Beldonia stop her insults. He’s certain that Beldonia already knows there’s something very wrong here and he suspects she’s concealing something to do with the death of Queen Elspera. Beldonia finally confesses that there was no accident. In fact, there was never even a body and Elspera simply vanished. Pandora tells them about the secret passageway behind Elspera’s painting in the Hall of Portraits that leads to an underground passageway with a door carved with the figure of a lioness. The Doctor finds this interesting as the lioness is a creature found nowhere else in the Universe but on Earth.

Pelleas and Erimem reach the top of the battlements and he tells her he often comes up here when he needs to think as the wind helps to blow away the cobwebs in his head. It’s the highest point in the Citadel and from here you can look out across the entire kingdom from the Cargas Mountains in the east to the shores of Lake Vanashor. Erimem finds the planet wild and savage, yet beautiful too and she‘s never seen sunsets like it. They look down on the forest where Pelleas’s mother is believed to have died and Pelleas remarks on how he believes she was murdered by an offworlder…like Erimem.

As Zixlyr continues his attack on Peri, she suddenly remembers that the aliens who attacked his ship were from Arcturus and she suggests that one of them could already be here on the planet and may have been responsible for murdering his sister. Zixlyr reveals that no one fired on his ship and the damage was self-inflicted when he detonated a device in the cargo bay to cripple, but not destroy his ship. Peri realises he did it so he could land on Peladon without going through the security checks. Zixlyr dismisses his dead pilot as an “unfortunate casualty”, but Peri says he’s just a petty, ignoble criminal who’ll go down in history as a grubby little murderer. She wonders if his sister would be proud of him and says if he truly wanted to find out about her death, he’d find out for certain who killed her and then expose them. That way, he’ll come out of this looking like a hero and not just a manic with a bomb seeking revenge. Zixlyr considers her words, but then reminds her of what his sister said about Pelleas and his mother. Peri points out that all she said was that she didn’t trust them, but she also implied something else was at work here, something dark at the heart of the Citadel. That doesn’t mean the rulers killed her. Zixlyr releases Peri and she promises to work with him and find who killed Alyxlyr so that justice can be done. The first thing they must do is find out where this heart of darkness is and her first idea is to look underground…

The miners are impatiently waiting for Elkin to join them at their pre-arranged rendezvous when one of them spots what they think is a new piece of mining equipment. The foreman asks everyone to stand back so he can see. They find an alien device which is emitting a regular bleeping noise. It appears to be a measuring device of some sort, but there are no readouts, just a countdown. No one’s seen anything like it before and only the foreman realises the truth. He urges everyone to run as fast as they can, but it’s too late and the bomb explodes…

The effects of the explosion are felt throughout the entire Citadel, even on the highest battlements. Pelleas calls to Erimem to move back from the edge, but the warning comes too late and the vibrations send her toppling over the side. She screams as Pelleas leaps forward and grabs her arms. Hanging over the mountain, she pleads with him not to let her fall.

Peri turns angrily on Zixlyr and accuses him of setting off his bomb, but he assures her this is nothing to do with him. He believes the blast came from the mines below and Peri immediately leaps to action and suggests they investigate.

Returning to the scene of the explosion, the engineer from Vega Nexos works as fast as he can to load the supply of stolen trisilicate ready to take aboard the Arcturan‘s spaceship. Arktos urges him to hurry as they don’t have much time. He points out a large piece buried beneath a dead miner not far away, but Elkin believes he’s already done more than enough to earn his 50% of the profit. He turns to Arktos and announces that he intends to take all the profits and the spaceship too. He pulls out a weapon but Arktos laughs and says that if he’s killed, his creditors will simply transfer their efforts to tracking Elkin down and extracting the money from his corpse. The engineer says he’s waited a long time for this moment so that’s a risk he’s happy to take. However, when he tries to fire the weapon, it doesn’t work. Arktos laughs again and says he’d always knew Elkin would try to double-cross him. His own weapon emerges from the pressure unit and blasts Elkin dead.

The Doctor and Pandora try to revive the Queen Mother after she was knocked unconscious by the explosion. Beldonia demands to know what happened as all she remembers is Pandora pushing her. The Doctor admits this is true, but adds that she was simply saving her life as she was about to be crushed by half a ton of falling stone. She looks over and sees that the statue of Aggedor has fallen down from the wall and hit the ground exactly where she was standing. The Doctor thinks the cause of the tremor came from the mine, so he decides to investigate in case there‘s been a cave-in while Beldonia alerts the infirmary and tells them to expect casualties. As they’re about to leave, Beldonia offers Pandora a sincere thank you, then she demands that the Princess get a move on instead of standing there dawdling.

Peri and Zixlyr arrive in the mine and find the dead bodies of at least twenty miners. There are no survivors as far as they can tell and Peri has found one who is barely older than a child. Zixlyr realises this was no accident. He has experience of the mines on Mars and he knows that when there’s a cave-in only the roof and upper walls collapse, but in this case there’s also damage to the floor. He suspects sabotage!

Arktos has completed the transfer of the trisilicate onto his invisible spaceship and he orders the computer to seal the cargo doors ready for take-off. He’s keen to get as far away from this miserable planet as possible, but things do not go as planned. A figure emerges from the shadows - and as it steps out in front of Arktos, he recognises it and calls out in surprise. A weapon is fired and Arktos is instantly disabled…

The Doctor admits to Pandora that he hasn’t been down to the mines of Peladon for some considerable time. Pandora says her father thinks mining is a fool’s game - there’s too much risk for too little gain. The Doctor says that’s easy enough to say when you’re rich enough to import your minerals from other planets, but Peladon is a poor planet and trisilicate is all it has. Pandora points out that Earth isn’t particularly wealthy either, or why else would her father want to arrange an alliance with this planet? She explains the situation and the Doctor realises for the first time that this is to be a marriage of convenience, not love. They soon stumble across a body and the Doctor identifies it as a native of Vega Nexos. What’s interesting is this man didn’t die from a rock fall, he was shot by a high impulse laser! Pelleas arrives and reveals Elkin was in charge of mining the new trisilicate stream. The Doctor asks Pandora to return to Beldonia with a message, but she realises he‘s just trying to get rid of her. He admits that he’s worried because whoever killed Elkin may still be roaming free, but Pandora refuses to be dismissed so easily.

The Doctor’s party is soon reunited with Peri and Zixlyr and the Doctor introduces them to Pandora and Pelleas. Zixlyr notes that the King’s family seems to attract death and disaster, then he makes an excuse about the atmosphere becoming unpleasant and leaves the mine. Pandora wonders what Pelleas could have done to Zixlyr to have made him so mad, but Peri changes the subject quickly and tells them Zixlyr’s theory about sabotage. Alpha Centauri then arrives and the Doctor rushes forward to greet his old friend. It takes Centauri a moment or two to realise this is the same man he met all those years ago, then he reveals that the person responsible for all this carnage was Arktos. Pandora has also heard of Arktos and describes him as the Scourge of the Nine Worlds, also known as the Silver Assassin and the Death Merchant. Pelleas is horrified to discover that this intergalactic criminal mastermind was here on Peladon as he thought they had him locked up on Arcturus. Centauri says he escaped, but the Arcturan authorities closed their borders in the hope of recapturing Arktos before he left their system. He obviously eluded them and managed to land here without being detected. Pelleas thinks that would be impossible, but Peri remembers the “ghost ship” they picked up on the radar just before Zixlyr’s ship crashed. The Doctor asks Centauri where Arktos is now and the ambassador becomes deeply embarrassed. Although his race is peaceful and they don’t believe in violence, Centauri admits that he shot Arktos inside his spaceship. Pandora thinks this is brilliant and is only a little disappointed when Centauri reveals that Arktos is only stunned. Pandora offers to return with some guards and says she’ll brief Beldonia on the casualties at the same time so that the bodies can be collected and the families informed. Before she leaves, she checks with Pelleas that their wedding is still on for later tonight and he promises her they can make their relationship work. After she’s gone, the Doctor tells Pelleas that Pandora will make a fine ruler. They ask Centauri to take them to Arktos, but Erimem asks if she can borrow a torch as she noticed something on the way in that she’d like to check out. It was probably just a trick of the light, but she thought she saw writing on the wall in her own language…

Beldonia surveys the damage in the Hall of Portraits and is furious that hundreds of years of history have been demolished in just a few minutes. Pandora joins her and is delighted to see that picture of the great Paladin and his imposing beard is still intact. She laughs, then apologises when she remembers that he was Beldonia’s husband. She tells the Queen Mother they both got off on the wrong foot when they met, but asks if they can pull together as both Pelleas and the planet Peladon need them. Beldonia refuses to back down and leaves for the infirmary where she says she has duties to perform. Pandora tries to call her back, but the old woman simply says she’ll see her at the wedding later. The Princess is furious with the bitter, twisted harpy and can’t understand why she won’t lower her shields just for once and open up. As she says this, the secret panel behind the portraits opens up again and the ghostly voice calls for Pandora to come down. Deciding she‘s had enough of real people for a while, the Princess enter the passageway willingly.

Going back down the tunnel, Erimem discovers she was right. She moves aside some fallen boulders and exposes the hieroglyphs she saw on the wall when they passed this way earlier. Peri can’t understand what they’re doing carved into the rock on Peladon and wonders if Arktos did it, but the Doctor confirms the words are Egyptian, not Arcturan. As far as he knows, there’s only one other race that writes in hieroglyphs, but they’re all dead. Erimem translates the words and says it’s a warning - “Four females of royal blood shall stand and fall. When the fourth falls, she will usher in the second reign of Sekhmet, the Avenger“. The rest of the words were destroyed in the rock fall. Peri asks who Sekhmet is and Erimem tells her she devours worlds!

Pandora finds herself once again standing before the door with the lioness motif. As she’s about to turn back, the door slowly opens of its own accord and the ghostly voice tells her it’s time they met. Pandora delays for a moment to remove a particularly irritating bit of grit from her shoe, then she enters.

Erimem explains that her ancestors met Sekhmet and her people still fear her, which is why she wears a signet ring as a talisman to protect herself. It has the same symbol that’s on the hieroglyphs and Erimem explains that Sekhmet’s sigil is in the image of a lioness. The Doctor suddenly remembers that Pandora spoke of a door carved with the figure of a lioness - the sign of Sekhmet!

Sekhmet first visited Erimem’s people at the time when Ra the sun god chose to live among them as a human. As he aged, his rivals began to plot against him, so he summoned his divine eye and transformed her into Sekhmet the Powerful One, the Avenger. Sekhmet slaughtered Ra’s enemies and waded in their blood - but she didn’t stop there. The raging lioness developed a taste for blood and began slaughtering every living thing in an orgy of killing. Ra ordered the High Priest of his temple at Heliopolis to pour out seven thousand jars of beer and dye it red with the juice of pomegranates. When Sekhmet saw this lake of blood, she couldn’t resist and drank deep until stupefied by alcohol. She was captured and imprisoned forever in a tomb of salt. Erimem’s ancestors thought they’d defeated her, but now she’s returned and she’s thirsty for vengeance!

Peri argues that Sekhmet is just a story or a myth, but the Doctor confirms that it’s true. Sekhmet was a god, at least to the Egyptians, but he adds that they’d be worshipped as gods too if they landed out of the blue amongst a technologically backward people. Erimem is surprised to learn that Sekhmet is actually an Osirian, a noble race of alien super beings who ruled the Universe millions of years before her time. She asks what Sekhmet is doing on Peladon and the Doctor guesses she crash landed here thousands of years before the Citadel was built. He explains that trisilicate is the hardest form of salt in the galaxy and Sekhmet was imprisoned inside it and blasted into space, and she’s been down here in the dark ever since, waiting and planning…

Pelleas returns to the battlements at the top of the Citadel and calls out to his mother. The ghostly voice responds immediately and he tells her they’ve captured the offworlder Arktos and he will shortly be taken back to Arcturus to face justice. Pelleas believes it’s over now and Elspera can rest in peace, but the voice tells him Arktos was not the one who murdered her. She tells him her killer was the one called Erimem…

Beldonia is starting to accept the fact that Pandora will be the next Queen of Peladon and there’s nothing she can do about it. She knocks on the Princess’s door and goes in to apologise for her earlier behaviour, but the room is empty.

The Doctor tells Peri that the old wives tale about salt warding off evil isn’t entirely spurious. Trisilicate is made up of negatively charged atoms which have steadily sapped Sekhmet’s energy and the longer she’s been in her prison, the weaker she’s become. The miners must have cracked open the tomb and ever since then she’s been growing in strength, leeching energy from the outside world. The real mystery is why hasn’t she escaped yet? Peri suggests she might still need the keys to her handcuffs and the Doctor congratulates her logic. The Osirians will have had other safeguards in place to restrain Sekhmet. He asks Erimem to read the hieroglyphs again and he realises they’re dealing with a blood-lock. It’s one of the strongest bonds in the Universe and only a specific type of blood - in this case the blood of four Royal females - can unlock it. Pelleas’s mother must have somehow stumbled across Sekhmet after the tomb was opened. Peri points out that Zixlyr’s twin sister, Alyxlyr, is also a Princess and she went missing shortly after becoming Ambassador to Peladon. That means there are now only two locks left in place, so the next likely victims will be Beldonia and Pandora. The Doctor sends Erimem to warn Pelleas while he and Peri go to track down the intended victims, but Peri tells the Doctor she needs to find Zixlyr fast. She reveals that Zixlyr thinks Pelleas killed his sister and he has a bomb. She races off and the Doctor turns to Erimem and says he hopes there’s nothing important that she’s not telling him…

Peri arrives at Zixlyr’s quarters and tells him his sister is dead and she was indeed murdered, but not by Pelleas. After she briefs him on what they’ve discovered, Zixlyr asks Peri where the Osirian’s tomb is, but all she knows is there’s a secret passageway behind one of the paintings. Zixlyr returns to his packing and Peri accuses him of having no honour or courage, but in fact he’s just retrieving his Xanthoid Volatiser. They leave to go in search of the tomb…

Erimem finds Pelleas on the battlements and tells him they have to go down to the throne room as Pandora and his grandmother are in grave danger. Pelleas says he knows already because his mother told him about a viper in their midst. He asks if it’s true and, not knowing what he’s referring to, she says it is. Pelleas turns on Erimem angrily and clubs her to the ground before she has a chance to explain further. Then he tells his mother he’s coming for her and he’s bringing Erimem with him…

Beldonia summons the King’s Champion Grok and asks if there’s been any sign of the Princess Pandora, but although he has men searching the Citadel there’s no news yet. He wonders if she may have gone for a walk outside, but Beldonia says nobody would do that in the middle of the night. The circumstances are exactly the same as they were with Elspera and Alyxlyr. There’s no trace of a body, they just simply disappeared. She believes the gods are angry because they’ve rejected the old religion. The Doctor joins them, having overheard their conversation, and she accepts that she should have told him the truth when they first met. She reveals that Pandora is also missing, but he has a pretty good idea where she might be. He asks Grok to fetch something for him, then asks Beldonia to take him to the Hall of Portraits.

The Doctor and Beldonia arrive at the door Pandora described and find the Princess’s slipper abandoned on the ground outside. They hear a terrible howl and the Doctor tells Beldonia it’s the key to opening the door. Grok joins them, accompanied by Aggedor, and he asks the Doctor to promise that they won’t harm her. The Doctor assures him that all they need from Aggedor is help battering down the door. He lifts a flaming torch and asks the beast to look into the flame while he sings the Venusian lullaby again. He tells the others to stand back, then Aggedor charges repeatedly at the door and eventually breaks through using the force of her horn. The creature howls out and Grok accuses the Doctor of harming her, but Beldonia is sure the cause is something else so she orders Grok to take her back to the kennels to be checked over. The Doctor asks Beldonia to leave too, but the old Queen Mother refuses. The Doctor points out that if Sekhmet has already killed Pandora, she’ll have broken the third lock and only needs the blood of one more royal female to break her bonds forever. While she’s still caged, they might still defeat Sekhmet, but free she will be invincible. Reluctantly Beldonia agrees, but she asks Grok to stay with the Doctor and declares that he should be the Doctor’s Champion now.

Erimem starts to wake up and finds herself bound. The ghostly voice addresses Pelleas as her son, but now that he’s seen Sekhmet’s true emaciated form he knows he’s been tricked and dismisses her as a wizened hag. She mocks him by claiming even his mother put up more resistance than he did. He realises she was the one who killed his mother and when she describes how she drank her blood, Pelleas rushes forward to attack her. Sekhmet traps him in a force field and the pain is so great he begs to be released. Erimem stands up and challenges Sekhmet, telling her she comes from the race that defeated her once before. Sekhmet insists that she wasn’t defeated, but betrayed by Ra and she swears he will pay for that betrayal. She releases Pelleas from the force field and he collapses, unconscious.

The Doctor enters the room and says he very much doubts Sekhmet will get the revenge she’s after as Ra has been dead for thousands of years. He asks where Pandora is and Sekhmet tells him she’s served her purpose and is with her ancestors now. The Doctor is furious. He knows Sekhmet didn’t have to kill Pandora as just a single drop of her blood would’ve been enough to open the seal. Sekhmet recognises the Doctor, but he mocks her and says her race falls into three categories - the good, the bad and the ugly. He says he can’t allow her to escape, but this makes her laugh and she doesn’t believe he can stop her. Three of the four dimensional seals are already broken and she only needs to open one more to gain her freedom. The Doctor points out that Beldonia isn’t coming, but Sekhmet says she doesn’t need her when she can have the blood of Erimem - a pharaoh removed from her own time stream, ironically by the Doctor himself.

Peri and Zixlyr arrive in the crypt and Peri can’t understand why the Doctor seems to be deliberately antagonising Sekhmet. Zixlyr realises he must be buying them time, so he arranges with Grok to distract their enemy while Peri and the Doctor rescue Erimem and Pelleas. Then they will seal the chamber forever with the Xanthoid Volatiser, which will detonate 60 seconds after it‘s activated. Grok raises his spear. Sekhmet reveals that she knows the Doctor is a Time Lord and from Erimem’s mind she’s learned that he has a TARDIS too. The Doctor attempts to make a deal with her - if she’ll release Pelleas and Erimem he’ll take her to whoever she wants to go in the galaxy. Erimem doesn’t trust Sekhmet and says she’ll kill him and steal the ship as soon as she’s inside, but the Doctor says that wouldn’t be a very good idea as the controls are isomorphic and will only work for him. Sekhmet laughs and finds his transparent lie very amusing. The Doctor is disappointed as the ploy worked before. Sekhmet tells him to prepare to die - but suddenly Grok’s spear comes out of nowhere and impales her. As she screams, the Doctor and Grok assist the unconscious Pelleas while Peri helps Erimem. Zixlyr urges them all to hurry as Sekhmet has nearly pulled the spear free. She swears revenge on the Doctor and hurls the spear towards him - but Grok valiantly steps forward and blocks the spear with his own body. The Doctor rushes over and attempts to staunch the blood, but Grok knows it’s too late and at least he can die knowing he’s a Champion.

Zixlyr turns angrily on Sekhmet and swears that she’s killed her last victim, but before he can act he’s blasted by burning energy from the Osirian’s eyes. Erimem steps forward and tells Sekhmet she’ll offer herself as a sacrifice in exchange for the lives of her friends. Sekhmet mocks her and says that’s no kind of bargain since she can already drink Erimem’s blood whenever she wishes. Erimem suggests that her blood will be all the sweeter if it’s offered freely from a member of the same race that encased her in this tomb - an atonement from the last of the pharaohs to the last of the Osirians. Sekhmet accepts the deal and Erimem seals the bargain by kissing her own signet ring which bears the sigil of the lioness, the symbol of Sekhmet’s own power and majesty. The Doctor urges Erimem not to go ahead and says there has to be another way, but then Sekhmet reveals that although she’ll accept the sacrifice, she will still drain all of Erimem’s blood and kill her friends as well.

The burning energy bursts out of Sekhmet’s eyes again and as Erimem’s blood passes over to her, the fourth blood-lock begins to open. The Osirian proclaims that she will soon be free, but Erimem corrects her and says she will soon be dead. She reveals that she’s just poisoned her own blood with distilled mandrake root from a capsule contained within her own signet ring. Sekhmet screams in horror as Erimem says this is the second time she’s been tricked with drugged blood. They’ll both be dead in just a few minutes and as Erimem collapses, the Doctor urges everyone to get out before the tomb collapses. Sekhmet threatens to tear the entire Universe apart, but the Doctor tells her she brought her destruction upon herself. Sekhmet believes she has just enough power left to end the Doctor’s miserable existence, but as she sends out the burning energy from her eyes, Zixlyr recovers from his injuries just enough to grab hold of the Osirian and distract her. He activates the Xanthoid Volatiser and tells everyone they have 60 seconds to evacuate before the explosion seals the tomb forever. Sekhmet threatens to burn out his eyes, but he says that would be a welcome relief from staring at her emaciated face. Peri calls to Zixlyr to come with them, but he knows he has to hold Sekhmet back until they’ve reached a safe distance. In any case, he believes his place is here with Alyxlyr. He asks Peri to save her friends, just as she saved his honour.

Peri revives the semi-conscious Pelleas and orders him to help Erimem back through the tunnels to the Citadel. Unfortunately the Doctor’s been severely weakened by Sekhmet and he doesn’t think he can make it, but Peri refuses to give up and physically drags him to safety. In the tomb, Sekhmet offers to spare Zixlyr’s life if he releases her, but he points out that his life is not hers to spare. He suggests they embrace death together - and as he grips her tighter, the Volatiser explodes and the entire cavern is reduced to dust.

The vibrations are felt back in the Hall of Portraits where Beldonia anxiously awaits news from the guard Nardo who she’s sent down the tunnel to find out what’s happening. Eventually Nardo calls out that he can see the others coming back, so Beldonia sends Frankis down to help too. She prays to Aggedor to let her grandson live and in return she promises to accede to all his future wishes - he can even marry whoever he chooses. Pelleas is the first to emerge and his grandmother rushes over to greet him. He tells her Pandora is dead and that Erimem has been poisoned. Beldonia calls for a stretcher, but Peri emerges and tells her they need another one for the Doctor as he’s badly hurt too. Pelleas thinks Erimem may already be dead, but the Doctor whispers to him weakly and asks for a knife. The King collects his grandfather’s dagger and the Doctor starts giving instructions to Peri…

Later, Alpha Centauri reports that he’s ready for departure. Arktos is secure in the spaceship brig and the Doctor’s TARDIS has also been located in orbit above Peladon so they can pick it up with only the slightest detour from their planned route. Centauri says he can’t stop thinking about Princess Pandora and the fact that he brought her here to die, but Peri promises him it wasn’t his fault. With Zixlyr dead too, Centauri’s going to have a lot of explaining to do to the governments of Earth and Mars. He had hoped to retire this year, but now he fears there’ll be many months of negotiation ahead to smooth things over. Peri thinks he’s the right person for the job and Centauri agrees. He asks Peri where they will be going next, but she doesn’t know. The Doctor arrives after visiting the kennels with Beldonia. It seems that Aggedor’s pain had nothing to do with breaking down the door to the tomb - they were labour pains and after a century of pregnancy, Aggedor has just given birth to a litter of cute baby Aggedors. Everyone is delighted, but none more so than Alpha Centauri who makes an excuse to return to his ship before anyone can see him cry. Erimem joins them and says she’s never felt better. Pelleas asks the Doctor what magic he used to purge the poisoned blood and he explains that Sekhmet’s attack on him weakened his own system so much that it triggered the regenerative platelets in his blood. They were still active when Peri performed the crude blood transfusion using the dagger and his Time Lord blood was able to enter Erimem’s body to eliminate the poison and revive her dying cells. Pelleas says the Doctor reminds him of his mother because she believed in science rather than superstition and the Doctor agrees that this has always been his motto and it’s never let him down so far, touch wood.

Peri says they need to get going now as Alpha Centauri is on a tight schedule, so the Doctor says goodbye to Pelleas and Beldonia, who graciously tells him Peladon is once again in his debt. But as they turn to leave, Erimem announces that she’s not coming with them. She decided to stay here on Peladon and says she’s never felt more sure of anything in her whole life. She’s loved travelling with them and she’s seen wonders beyond her imagination, but all this time she’s been evading her true destiny. She says she was born to rule and that is her purpose. She understands Peladon, its society, its politics and traditions and it’s very much like the world where she was brought up. It’s also a world that needs a strong ruler and although Pelleas is a good man, he’s young and wants to run before he can walk. She thinks she can show him how to become a great ruler as both his mentor and his wife. Peri is shocked when Erimem tells them Pelleas proposed to her an hour ago and she intends to accept. They’re genuinely fond of each other and that may blossom into love. Peri doesn’t think Erimem is making any sense, but the Doctor knows Erimem has made up her mind. Erimem gets upset when Peri starts arguing with her as Peri is the only true friend she’s ever had. They hug and cry, then Peri says she thinks she’ll make a great Queen and with a husband like Pelleas they‘re guaranteed to have good looking kids. Erimem asks them to stay for the wedding, but both the Doctor and Peri think it would be best if they go now. They say goodbye and the Doctor tells Erimem that he thinks she’s doing the right thing. In fact, he’s more worried that Peri will become uncontrollable without Erimem’s influence.