Two youngsters, Prince Kalkin and Sararti, struggle wearily to the top of the mountain where they plan to fulfil their destiny. Sararti momentarily slips, but she’s caught by her lover. They’re both relieved that she didn’t fall to her death as they’re not ready for that yet and they still need to climb just a little higher. She wonders if what they’re planning is going to hurt, but Kalkin doesn’t know, as he’s never killed himself before. They settle on a ledge near the top and look down. With such a long drop onto the rocks below, their deaths will at least be quick. Kalkin tells Sararti he would rather die right now and be with her for that moment than let the others take her from him -- but there’s still time for her to change her mind if she wants. They can climb back down to the city, forget this ever happened and let the others come for them when they will. But Sararti has made up her mind and she agrees they should both die together. They hold hands and prepare for the moment, then they look into each others eyes and speak aloud their wedding vows in defiance of parents, gods and men. Before they can complete it, they’re interrupted by the sound of the TARDIS materialising nearby.

Inside the TARDIS, Lucie asks if the Doctor has been able to bring her closer to home than 1974, but he refuses to commit himself. He explains that piloting the ship isn’t an exact science, which surprises Lucie as she thought that’s exactly what it was. They decide to look outside and are greeted by the beauty of the mountain sky -- and then Lucie immediately drops over the edge only to be saved by the Doctor’s speedy reaction. He pulls her back to safety and when she rebukes him for parking so close to the edge of the cliff, he changes the subject to the marvellous view and the clean air. Lucie notices they’re being watched by the young man and woman, and the Doctor hopes they’re not interrupting anything. Lucie points out that there are two young people in the middle of nowhere, with not a soul for miles around, so it’s pretty obvious they’re interrupting big time! Kalkin introduces himself and Lucie is delighted to discover he’s a Prince. Sararti asks them for forgiveness and says that when they spoke of defying the gods they meant the impostors, not true divinity. Kalkin asks the Doctor if he’s here to intercede for them, but he says it depends on the situation. The Doctor challenges Lucie to read the signs -- these youngsters climbed the cliff alone, dressed up in their finery and heedless of any damage to their clothes, so it seems obvious they have no intention of going back home… ever. This isn’t some lovers’ tryst on a hillside, it’s a one-way trip. Kalkin and Sararti confirm the worst: they’ve come here to die! The Doctor decides to intercede after all, and Sararti starts crying. Lucie takes her to one side for a private chat and explains to her that no relationship is worth killing yourself for.

A man named Tayden is also climbing the mountain, and he uses a two-way radio to communicate with General Ares back at base. He’s spotted the two youngsters at the top, but they’re not alone. Although he can’t tell whether the strangers are reinforcements or revolutionaries, he’s sure he can handle the situation and talk them down. The General informs him that Zeus is as angry as hell, so they can’t leave this to Tayden alone, and he‘s been ordered to send in the chariot…

The Doctor calls out to Lucie not to wander off too far and gets a rude gesture in return. Kalkin wonders whether she’s a god of anger and the Doctor says that’s one way of looking at it. Kalkin believes the Doctor and Lucie came here in answer to his prayers, and asks the Doctor to use his special powers to protect them from the chariots which will no doubt be here soon. The Doctor is struggling to persuade Kalkin that he’s too young to be tired of life already, but the look on the young man’s face is the same one he used to get all the time from his grand-daughter. He knows that when you’re young, every drama seems like a crisis and everything seems like the end of the world.

Lucie guesses that Sararti’s parents don’t approve of her choice of boyfriend, but the young woman says it’s worse than that. They can never be together and she’s disappointed Lucie thinks she’d be so melodramatic. A figure appears, dressed in a soldier’s uniform, and Sararti recognises him as Tayden and realises he must have been sent to talk them round. Tayden reaches Sararti and tries to talk her out of doing anything stupid, and Lucie is pleased that the woman obviously has friends who care. Tayden tells Sararti that she can’t escape her destiny and no purpose will be achieved by trying to deny it. Lucie assumes Sararti has been promised to someone else, but Tayden says her time is approaching and she must obey the wishes of the gods. Lucie thinks it’s like Romeo and Juliet and then realises this isn’t necessarily a good thing. Suddenly they hear a noise getting closer; Kalkin says it’s the chariots of the gods -- but the Doctor recognises it instantly as a helicopter! Kalkin calls to Sararti and says they’re running out of time, but the Doctor refuses to let them jump off the mountain. They end up struggling on the very edge of the cliff, and when Sararti rushes over to join them, Tayden pulls out a gun. Sararti tells him she’s not frightened of his “magic staff” and invites him to shoot her, but Lucie jumps on the soldier and they fight over the weapon.

The helicopter lands and the group by the cliff soon find themselves surrounded by General Ares and his troops. The Doctor tries to speak, but he’s clubbed to the ground. Kalkin mocks the General and says he’ll never take him alive -- or more precisely, he’ll never take him and stay alive! He then pulls out a gun and shoots Ares before the Doctor can disarm him. The General is in pain, but is still alive. The Doctor and Lucie order the other soldiers to break out their medical supplies, but they seem confused by the request until the General explains that he means the Casket of Healing. With Lucie’s help, the Doctor performs emergency treatment on Ares, but he’s losing a lot of blood and they need to get him to a hospital quickly. The soldiers load everyone aboard the helicopter and head off for the Chamber of Incarnation…

The goddess Hera is woken from her sleep by the intercom. She wearily orders her husband to go away, but he says he wouldn’t have woken her unless it was important: Ares has been shot and is in a critical condition. Usually Zeus could handle it himself, but their son Ganymede has been plying him with wine all night and he’s too woozy to operate the machine now. In any case, it’s Hera’s turn, so she grumpily gets out of bed and tells him she’ll be there in ten minutes. He also tells her that Tayden is bringing back some unexpected visitors.

In the throne room, Zeus is struggling to understand the controls of the two-way radio, so his son Ganymede shows him how to operate it. Zeus thanks Tayden for saving the General’s life and says that he wishes his son, the ungrateful whiner Kalkin, was as loyal as he. The two lovers have been taken into custody and are brought before Zeus, whereupon Kalkin insists on the right to take his own life. Zeus refuses, but the youngsters say they will never co-operate as now they have the ‘true’ gods to protect them, so Zeus decides to visit the Chamber and meet these new gods. Kalkin accuses his father of murder, but he says he’s heard it all before and orders them to be taken away. He gives instructions for the lovers to be chained on opposing walls to see if that cools their ardour.

The Doctor and Lucie are getting worried about the General as he’s lost consciousness and time is running out. The helicopter has taken them to this civilisation’s equivalent of a hospital, but now they seem to be waiting outside an area described only as the Portal of Cleansing. Tayden tells them that the outer door must close before the inner door will open. They can’t all pass through at the same time, so he orders the Doctor to wait outside. The Doctor refuses and tries to squeeze in with them, but the soldiers force him to stand back as the outer door closes. Moments later, a bearded man and a boy approach and the Doctor asks if they know how to open the door. The man explains that the Portal washes those it admits of bad humours ready for the Chamber of Incarnation, but the cycle takes several minutes so even if he entered now, the operation would be over by the time he arrived. The Doctor is surprised to hear the man talk of operations rather than the ‘magical casting out of demons,’ because everything else here has been dressed up in fancy language. For example, the man calls his walkie-talkie an ether trumpet, and the Portal itself is clearly a decontamination chamber. The man laughs at the Doctor’s big words, then introduces himself as Zeus, lord of the skies and bringer of storms. The Doctor wonders if he’s going crazy, but Zeus tells him not to concern himself with General Ares, as they have the facilities to help him.

Inside the decontamination chamber, Lucie is worried about the delay but Tayden tells her they must wait for the sprites to gather in the air to do their work. As the cleansing begins, the room is filled with ‘fairy lights’ and Tayden tells her to close her eyes. To her shock, she discovers she can see through Tayden’s clothes, and she’s even more embarrassed when he points out that he can see through hers too. That’s why the people tend to close their eyes when they’re in here. The process is complete and the group moves through into the main operating room.

Zeus invites the Doctor up to the observation gallery, and on the way, he thanks the Doctor for saving the life of his son Kalkin. It would have been most inconvenient if Kalkin had killed himself, as Ganymede is only 15, which is a little too young to assume the duties of next-in-line. The Doctor is surprised by Ganymede’s lack of concern that his brother was ready to take his own life, but the boy says he’s a coward who let his father down. Zeus orders his son to leave while he discusses matters of a theosophical nature with the Doctor, but the Doctor argues that they really ought to be talking about theophany instead, because this isn’t about real gods but the appearance of gods. The heavenly powers on display here are far too mechanical for his liking and he doesn’t find Zeus’s demeanour very god-like. He wonders how long Zeus has been pulling the wool over people’s eyes...

Hera asks for the patient to be brought in and looks down at the injured Ares with sorrow. Lucie tells Hera about the plasma she and the Doctor gave Ares to replace his lost blood and says they got him here as quickly as they could, but Hera tells Lucie to stop jabbering, as she’s about to witness a divine act. Tayden takes Lucie to one side so they can let the Incarnators do their work. Meanwhile, the Doctor and Zeus arrive in the observation gallery and the Doctor knocks on the glass and waves to Lucie down below. He notes the equipment inside the Chamber of Incarnation and blatantly asks Zeus whether it’s legal. Zeus can call this room whatever he likes, but coming up with a funny name won’t change the fact that he’s using an RSK Device, which is banned in every civilised world. Zeus finally realises that the Doctor doesn‘t come from this planet.

Hera orders Lucie and Tayden to be quiet as she needs to concentrate. She begins the procedure by placing a helmet on Ares, which Lucie finds odd as the General was shot in the chest, but Tayden tells her it’s part of the ceremony. The Doctor is having similar concerns and wonders why the doctors aren’t paying more attention to the General’s wounds. Zeus tells him Ares is dying, but the Doctor says if that’s true then Remote Synaptical Kinesis isn’t going to help him… unless… Suddenly the Doctor realises the truth -- they’re planning to transfer Ares’ mind into Tayden’s body before the General’s body dies. This will only work if the two bodies are genetic duplicates, and it dawns on the Doctor that Tayden must be a clone of the original Ares. Zeus confirms that Tayden is a copy of the General, 30 years younger, but the Doctor realises this means the process will wipe Tayden’s existing mind completely and he would effectively cease to exist. Hera tells Tayden it’s time, and the young soldier says goodbye to Lucie and tells her he enjoyed meeting her. When he explains that Hera will transfer the mind of Ares into his body, Lucie is horrified. Tayden tells Hera he’s ready, and though Lucie tries to persuade him not to go through with it, he says he was born for this purpose. She thinks this is murder and points out that Tayden will be wiped like an old video. The process begins, and although Lucie continues to pleads with him, it’s too late.

Zeus tells the Doctor that if one is an important deity, it pays to have a spare body or two lying around. Kalkin isn’t really Zeus’s son at all, he’s his clone; when Zeus wears one body out, he just moves his mind into a new one. Ganymede will be the next in line after Kalkin. Cloning itself is easy, but they can’t handle accelerated growth, so after they’re “born” they have to age naturally. The Doctor argues that Kalkin is now a human being in his own right, but Zeus regards him simply as a spare body. At the moment Ganymede’s synaptic links have yet to cement themselves in his brain; thus, a mind-transfer before the age of 16 won’t hold. The Doctor tells Zeus that if he’d known that saving Ares’s life would lead to the death of Tayden’s mind he wouldn’t have done it. Zeus knows he’s become an ugly pock-marked despot swilled with wine, but this process will allow him to continue living a life of luxury while staying young. The Doctor argues that he’d willingly donate a kidney or a heart to a member of his family, but he’d draw the line at wiping his mind so that a relative could take over his body. He says Tayden only went willingly because he’d been brainwashed for years. But it’s too late to argue now, as the process is complete. Zeus applauds Hera on another success as the young body of Tayden, now containing the mind of Ares, revives. Lucie tries to talk to Tayden, but the man she’s speaking to is now the General. He thinks Kalkin should pay for shooting him, but obviously he won’t do anything that might damage the future body of Zeus. He hopes Zeus will live long enough for Kalkin to become too old and be freed from his contract -- then he’ll hunt him down. Suddenly, the original body of General Ares splutters and they realise he’s still alive. Lucie pleads with them to reverse the process so Tayden can be restored to normal, but Ares picks up a knife and stabs his older body, finally putting an end to the matter.

Zeus decides to retire to his chambers so he can talk to the Doctor in private. Ganymede has laid out supper for them, but the Doctor isn’t hungry. Zeus expresses his dissatisfaction with the “ungrateful brat” Kalkin and says the boy had a wonderful childhood with his foster parents. He now only has a few months left to serve in his position; then he becomes too old for the process to work, as his mind will be too ingrained to wipe. When that happens, the next clone in line -- Ganymede -- will take his place, and Kalkin will be free to lead a normal life outside the palace with a fat pension. Until then, any day might be his last, but then the same could be said about anyone. Zeus believes it would be a waste to let him die as he’s got a thousand years of knowledge and experience to share, and without his people, this entire civilisation would fall apart. He reveals that he was the pilot who originally brought the ‘gods’ to this world and the others were his crew. The Doctor suggests that even with immortality there will be loopholes: accidents; someone being too far from their clone at the time of death; power failures; mental illness etc. There’s a reason why RSK machines are illegal: Remote Synaptical Kinesis isn’t an exact science, it’s an art, and the subjects who undergo the process can lose things without even realising. With cloning there can sometimes be a generational loss, and in cases where the clone isn’t a perfect match, the mind won’t transfer properly. Zeus has long suspected that kids today are a lesser breed, which explains why Kalkin is such an irritation, but the Doctor says the boy is just thinking for himself. Kalkin was smart enough to resist his father, and maybe he’s the only one around here who’s sane! At that moment, Lucie is brought in by the guards. The Doctor introduces her to Zeus and she recognises him straight away: he’s Kalkin, but grown old, fat and ugly after a decade of fine living and the worries of a ruler. Zeus turns to the Doctor and asks if he has a vessel in orbit, and before Lucie has a chance to correct him, the Doctor says he has.

Hera is finding the temperature uncomfortable with all the machinery switched on, so she and Ares step outside into the night. The bird song reminds Ares of the time they first stepped off the ship all those years ago. Hera notes how well he seems to be adjusting to his new body and he agrees that it’s fantastic. He compliments her on her skill with the Engine of Incantation and adds that Tayden looked after the body well. Not all the clones are as diligent in their duties, and Hera dreads to think what trouble she’s going to have with hers. Ares suggests cancelling her oldest daughter and moving on to the next applicant, but Hera has no wish to be a teenager again. She starts to cough, and fears her time will soon come as she’s beginning to feel old. She asks Ares about the Doctor, and they agree he must be from off-world as he speaks about concepts and ideas they’ve not permitted outside the palace for centuries. She wonders if perhaps the Doctor can help, and reveals that the machine hasn’t been working like it should for some time and that they’ll have trouble repairing it because there’s no way to obtain the necessary parts. Ares reminds Hera that talk of other worlds is forbidden, but she was the one who forbade it. When they first came here they agreed that this would be their home and there would be no talk of Earth or of science. For centuries, they’ve enjoyed the fruits of that deception, but their numbers are getting fewer with each generation due to accidents, suicides and the fact that some of the original crew refused to be cloned. Ares remembers when they experimented by transferring their minds into multiple clones simultaneously. It was fun for a few weeks, but played absolute havoc with their seating arrangements at dinner as everyone claimed to be the original. That was when they lost Athena (who was a bitch, every one of her) and Poseidon (who before the whole god-thing was called Geoffrey).

Zeus takes his guests to see the Incarnation Chamber; although the Doctor objects to the use of this equipment, he seems genuinely impressed and can admire the workmanship. The RSK device is an antique to the tenth power and it’s a miracle it’s lasted all this time. Lucie is angry with the Doctor and reminds him they’ve been using the equipment to kill their own children. Zeus orders her to be silent and asks the Doctor if he can appreciate his desire to serve his people eternally, but instead the Doctor suggests that he’s sacrificed progress and that there’s a reason human life spans are so short. Zeus isn’t interested in DNA, and although he doesn’t object to breeding for pleasure, he prefers to make exact copies of himself. Unfortunately, if the machine starts to break down then the copies won’t be perfect and their society will fall apart. Zeus asks if the Doctor can fix the machine, but he says it needs a complete overhaul and he’s not a mechanic. Unfortunately, Zeus has been losing whole chunks of his memory every time he transfers; as Lucie puts it, the human photocopier is running out of toner. Zeus says he doesn’t need the Doctor to do the work himself, just to get the replacement parts from the nearest supplier. If he refuses then Lucie will be Zeus’s insurance.

Later, Zeus visits Lucie on the pretext of checking whether the room is to her liking. She rebukes him for walking in unannounced as she might have been in her altogether, but agrees that the view from the window isn’t bad for a glorified prison cell. He asks if she and the Doctor are a couple, and when she says they aren’t he’s pleased -- not that it would have made any difference, of course. He invites her out for a moonlight walk around the garden, but she’s more interested in talking about Kalkin and Sararti. He admits that their love is a wondrous thing, but then he shows her the ‘new’ Ares and Hera in the garden. Zeus explains that she’s his wife and they’ve been together since they first came to this planet a thousand years ago. Their love lives forever, just like Kalkin and Sararti. Suddenly Lucie realises that Sararti is a clone of Hera, just as Kalkin is a clone of Zeus. It’s only natural that the two youngsters will fall for each other, but Lucie says that’s no excuse for wiping their souls to make room for their elders’. Zeus starts to discuss his love life with her, but she’s uncomfortable with the level of detail he’s providing. Zeus reveals what’s really on his mind: he likes Lucie and thinks she’d be an interesting experience. He’s already guessed that she’s attracted to Kalkin, his younger copy, and he reminds her that very soon he’ll be Kalkin again. If she turns him down, he’ll take a lock of her hair, make as many copies of her as he wants, and then do with them as he pleases. She accuses him of being a monster -- and then the Doctor appears, having climbed over three balconies to get to Lucie’s room. Suddenly they hear Ares calling for help from the garden below, and see that Hera has collapsed… Everyone races to help her, but she knows she’s dying. Zeus urges her to stay calm, but the Doctor thinks she’s having a heart attack and from the look of things, she’s not going to survive. Zeus sends orders for the Chamber of Incarnation to be prepared.

Kalkin and Sararti are still chained to the walls in the dungeons, and they amuse themselves by taunting the guards with talk about their ‘secret’ escape plans. Sararti thinks the mortals on this planet are so lucky, yet they don’t even realise it. Before these events she was just a timid, stupid, weak-willed girl and did everything she was told -- even when she went along with Kalkin to the cliffs -- but now she’d willingly chose to do that, and would even fight and kill if she had to. They’re interrupted by the arrival of the young General Ares, who orders the guard to unchain the prisoners. He tells them Lady Hera is dying and it’s time for Sararti to surrender her body. Kalkin objects, but to no avail, and Ares decides he should be forced to go with them and watch the transfer…

In the operating room, Zeus panics as Hera’s life signs start to fade. He calls for the replacement body, but the Doctor still wants him to reconsider and give Kalkin and Sararti a chance. He says this is the perfect time for a new beginning, but Zeus argues that living forever is no good without the love of his life. The two prisoners are dragged in and as Sararti is strapped to the table, Kalkin swears vengeance on his father. Suddenly the Doctor announces that it’s too late as Hera is already dead. Zeus refuses to listen and believes it’s just an attempt to distract him, so he goes ahead with the transfer. Sararti starts to come round and demands to be unstrapped. She crosses over the Kalkin and then, to his horror, addresses him as her son. She joins Zeus and urges him to wipe Kalkin’s mind and get into his body as soon as possible. As she encourages her husband to move closer for their first kiss, Lucie whispers to the Doctor that she seems to have recovered from the transfer very quickly compared to Ares. When she saw this happen before, the effect made Ares woozy for several minutes, but Hera got up as if nothing had happened. Hera decides it would be a good idea to put her old sick body out of its misery and asks if anyone has a knife. Zeus points out that the body is already dead, but then Sararti reveals the knife wasn’t for Hera, but for him! She lunges forward and thrusts the knife several times into him, on each occasion swearing revenge on behalf of his previous victims. Everyone rushes forward to disarm her as she declares her love for Kalkin…

Later, Lucie is impatient for news and believes the Doctor should be doing more to help, but he says it’s not a particularly complex operation and there are plenty of doctors here who can fix stab wounds. They’re surprised to see Kalkin has been released, and he tells them that he’s come to an ’understanding’ with his father. Unfortunately, Zeus is now dying. Kalkin takes them to the hospital, where they find Ganymede watching over his mortally wounded father. Zeus assures his younger son that he won’t die and will be reborn in Kalkin’s body, but Ganymede says he wants to be the one who donates his body. When Kalkin arrives, Ganymede turns on him angrily, then storms out, accusing his older brother of not being worthy of the honour. Zeus admits that he’s going to have to place himself in the Doctor’s care after all. Kalkin sides with his father and tells the Doctor he must operate the machine for them and save Zeus’s life. The Doctor objects and says it will achieve nothing. He asks why Kalkin has had a sudden change of heart after everything he fought for, and the young man explains that Zeus has finally found a way to control him. The Doctor knows that both Sararti and Kalkin were prepared to die for their beliefs, so he tries to work out what Zeus could possibly do to influence them. He suddenly realises that the weapon Zeus is using against them is Lucie. Zeus has lost his soul mate and now he wants revenge. If the Doctor refuses to help then the cloners will get to work and Lucie will die in a new and interesting way every day for a hundred years. Lucie points out that it won’t really be her, but then Zeus mocks her for having such a dismissive attitude to the suffering of clones. Kalkin pleads with the Doctor to agree.

Sararti arrives, having heard the news, and is angry with Kalkin for accepting Zeus’s terms after everything they’ve been through, but Kalkin is despondent and believes his father has finally won. The Doctor orders that the machine be switched on. Lucie protests, but Kalkin argues that he doesn’t want to be responsible for other people’s deaths. After a few seconds, the Doctor switches the machine off and says it’s over. The body of Kalkin gets up and speaks with the arrogance of Zeus, then he turns his attention to Lucie, who backs away in revulsion. He tries to kiss her and she slaps him, but he orders the guards not to retaliate as he recognises the foolishness of the young. As the guards shout out the traditional rally cry to mark the ascension of a new King, Lucie whispers to Sararti that they should leave before it’s too late…

Lucie and Sararti climb once again to the top of the mountain and eventually they reach the summit where they first met. Sararti wants to jump straight away, before the chariots can find them, but Lucie says they’ve not come here to die but to destroy the TARDIS by crashing it. She believes that by destroying the ship, the Doctor won’t be able to obtain the replacement parts needed to repair the machine. They’re too late to save Kalkin, but they can still save everyone that comes after him. Sararti agrees, but before they can act they see Zeus’s soldiers coming towards them in the helicopter. The Doctor and Zeus are also aboard and the Doctor urges them to go faster, worried about what his friends plan to do. It’s revealed that Zeus is actually Kalkin, who was merely putting on a performance in order to convince the population that their god was still alive. The performance was obviously very effective if it convinced both Lucie and Sararti. The helicopter comes in to land, cutting the two women off from the TARDIS. In desperation, they run to the edge of the cliff and threaten to throw themselves off. The Doctor pleads with them to stop, but Lucie accuses him of not caring any more. Kalkin steps forward and tries to reassure Sararti that he isn’t Zeus, but they don’t believe him. He reminds her that they took their marriage vows on this very spot, something only the two of them would know. He explains that he has taken Zeus’s place and the four of them are the only people that need ever learn the truth. The Doctor tells Lucie that the toner in the photocopier has finally run out. Zeus isn’t actually dead, but his memory is stuck within the RSK device, waiting for another body. Everyone agrees that it should stay there. Lucie is worried about the other immortals, such as Ares, but Kalkin points out that as long as they think he’s Zeus, no one is going to argue with him. He and Sararti can finally be together -- not forever, but at least for their natural life times. Sararti and Kalkin were ready to leap from the cliff, but now they must be ready to make a different kind of leap -- a leap of faith… till death do they part, which hopefully will be a long way away. The Doctor and Lucie say their goodbyes and their new friends realise they won’t be coming back. They’re on their own now, but they have a life together and they mustn’t waste it.