Somewhere, the events of history are being recited -- but something is wrong. The recorders can no longer remember what happened, and the stress of holding history together is driving them mad...

The Doctor and Charley celebrate their victory over the Daleks, trapped in a paradox and cut off from the rest of Time. The Time Lords will release them from the loop eventually, as much of history depends on their actions... but Romana has a score to settle with them, and will no doubt let them stew for a while. But as the Doctor sets course for their next destination, a fleet of battle TARDISes materializes around his own ship, just like the fleet the Doctor slipped past once before. This time, he realizes that they’re after him -- and Charley. CIA Co-ordinator Vansell and President Romana are already on their way...

The Doctor attempts to weave his way out of the trap, but one of the battle TARDISes fires time torpedoes at him. If he dematerializes to avoid them, the fleet will pluck his ship out of the Vortex; if the torpedoes hit, the Doctor and Charley will be frozen for centuries, giving the Time Lords plenty of time to break in. The Doctor refuses to give up, however, and at the last moment he and Charley are saved by a wave of time distortion which sweeps past, stealing vital seconds from the web of Time. By riding the crest of the wave, the Doctor gets past the battle TARDISes, which are unable to track his turbulent path. By the time the disturbance dies down, the Doctor and Charley have escaped.

Apparently satisfied, the Doctor tells Charley the time has come to celebrate her birthday, and presents her with a single exclusive invitation to a thousand-year party in a distant pocket of time and space which the Time Lords know nothing about. Sadly, there’s only one invitation, but the Doctor promises to pick her up again in a year’s time while he takes care of trifling business elsewhere. Charley isn’t fooled for a moment. She knows the truth; by rescuing her from the R101, the Doctor has broken history. She’s supposed to be dead, and the Doctor is taking the responsibility upon himself -- confident and carefree that nothing will go wrong, like Peter Pan living a life of adventure in Never-never-land. But while Wendy shared Peter’s adventures for a time, she had to grow up eventually. Charley chose to stow away on the R101, she chose to travel with the Doctor, and she understands the consequences of those decisions -- and thanks to the Doctor’s instructions during the Nimon invasion, she knows what the Fast Return Switch does. Before the Doctor can stop her she presses the Switch just once, and the TARDIS returns to its previous location, materializing in the path of the time torpedoes just as they detonate...

Three hundred years later, Celestial Intervention agents Kurst and Levith finally break into the Doctor’s TARDIS. He’s beginning to recover, and they send him to the President’s battle station, locate Charley, and prepare to install her in a space-time converter. Charley begins to recover, disoriented, but not so disoriented that she fails to take offence at Levith’s patronising attitude. Levith assures her that the Doctor is all right, and that they’re simply preparing Charley for a small procedure which shouldn’t harm her -- if she doesn’t resist...

The Doctor revives, deliriously reliving a few moments of a past adventure with Mary Shelley and Lord Byron before he recovers and realizes that he’s in a Time Station. Vansell attempts to interrogate him, ignoring the Doctor’s taunts and gibes; the Doctor has been brought here to discuss Charlotte Elspeth Pollard. The Doctor invokes the Archetryx Convention and demands a fair trial, but Romana arrives and assures him that Charley will not be harmed. However, the Doctor must be made aware that the time distortion which enabled him to escape earlier was not a random event. The Time Lords have detected many such distortions recently -- and they now believe them to be caused by particles of anti-Time. The Doctor doesn’t know whether to laugh or not; anti-Time is a pseudoscientific concept with more basis in superstition than reality. According to legend, when Rassilon created the Eye of Harmony, Time was pinned down to one continuous history -- but as every action has its equal and opposite reaction, the creation of positive Time created a mirror universe of anti-Time, a force as destructive to causality as anti-matter is to positive matter. If the Universe of anti-Time really exists, it’s a chaotic realm with no past, present or future; just an endless, meaningless, ever-changing Now.

The Doctor doesn’t believe such a place exists, but Romana reveals that the web of Time is near breaking point. History has changed on several important worlds, including Earth, where the wrong President was elected into control of a major landmass. The initial outbreaks of time distortion have now been traced -- to the times and places which the Doctor has visited with Charley. The mere fact of her survival has created a breach in space-time, a living gateway through which particles of anti-Time are flowing into this Universe, shattering causality. The Matrix has been turned over completely to anchoring the web, but it’s breaking under the strain -- and what’s left has projected a horrific future. Vansell reveals that the Doctor is inside a projection unit, an Eighth Door through which he casts the Doctor into the Matrix to see the future for himself...

The Doctor finds himself in the ruins of a once proud city, the skies dark with smoke, but not so dark that the Doctor can’t recognise the constellations. A sad old man, whom the Doctor finds terribly familiar, confirms that this world was once called Gallifrey -- but it is now the empire of Zagreus. The Doctor recognizes the name from an old nursery rhyme, but as he tries to recall the details, he is transported to a vast arena which was once the Panopticon. The crowd chants viciously as the cruel Imperiatrix Romana takes the stage and presents to her people the Dalek Emperor, trapped with his people in a time pocket. The Emperor demands to be released, arrogantly convinced that his race is required to maintain historical causality -- but instead, Romana passes judgement and obliterates the Daleks from history completely. The Dalek Emperor, realizing too late what is happening, begs for pity -- but Romana simply scoffs as the Daleks are crushed into oblivion forever. The Doctor is appalled, but as he protests this cruelty, the angry mob turns on him, prepared to tear him to pieces...

Vansell pulls the Doctor out of the projection just in time. Though shaken, he refuses to accept that saving Charley’s life was wrong; if Romana wishes to put Charley back on the R101, she’ll have to erase the Doctor from the whole of history first. As long as he lives, he’ll find a way to save his friend. But Romana reveals that there is already another way -- albeit a potentially dangerous one. According to Vansell, certain esoteric records in the Matrix have provided an alternative. Just as particles of anti-Time are travelling through Charley, so the Time Lords can use her as a conduit to travel the other way and stop the threat at its source.

Kurst and Levith are already at work in the Doctor’s TARDIS, setting up a proton accelerator to transform Charley into a living breach in space-time. Charley braces herself, and tells Levith to give the Doctor her love, though she believes Levith won’t understand such a concept. Kurst activates the converter, and Charley’s body twists out of time and space completely...

The Doctor is concerned, but Romana assures him that the change will only be temporary, and that once the flow of anti-Time has been stopped, Charley will be free to go. The Doctor thus accepts her plan, and accompanies her and Vansell to the bridge of the Time Station -- which is staffed with a skeleton crew of Interventionists due to the secret nature of the mission. Levith contacts Vansell and reveals that Charley has become a gateway, through which she can see the whole Universe. “And the gate of Zagreus opened before him...” But as the Time Station dematerializes, the Doctor’s TARDIS console overloads and the TARDIS is sucked through the breach itself. The Doctor begs Romana to abort the mission, but they’re already committed and can’t stop now. The Time Station passes through the breach...

As the Doctor’s TARDIS loses power, so does the space-time converter, and Charley returns to her natural human form, badly shaken by her experience. Kurst and Levith, also shaken, check the destination monitor and find that it can’t settle on temporal co-ordinates. They are in a universe without Time... yet strangely they’ve materialized on a solid surface. Charley leads them outside, where Levith sets up a beacon to guide the Time Station to them. Assuming, of course, that the Station made it through the breach before it closed up...

The Time Station materializes, but its sensors, calibrated to operate in a Universe of linear Time, are overloaded with useless data. The Doctor suggests just opening the windows, as it were, and the Under-Cardinal lifts the observation ports to reveal a universe of constant motion and chaos -- with one fixed point, a static planetoid which cannot have originated in this maelstrom. The Doctor theorizes that his TARDIS would naturally have been attracted to the one safe place for it to materialize, which seems confirmed when the Time Lords pick up a signal from a time beacon and a TARDIS signature -- although the TARDIS signature is too scrambled to identify clearly. The Time Lords set course for the planetoid, but as they approach, they lose the signal -- and the Doctor realizes that it’s being affected by time distortion.

As Levith waits impatiently for the Station, Charley and Kurst see a forest of metal spikes in the distance. Charley sets off to explore, unaware that Kurst and Levith aren’t following her -- something has gone wrong with the beacon and they’re desperately trying to get it back under control. Nevertheless, Charley isn’t alone -- for something speaks to her in her own voice, and she finds herself facing what appears to be her own ghost. More spectres surround Charley, identifying themselves as the people who never were. Kurst and Levith open fire on the ghosts, distracting them while Charley flees to safety -- but the ghosts reform and descend upon Kurst, consuming the essence of his life. Charley and Levith try to flee back to the TARDIS, but the ground splits open before them, and the beacon and TARDIS tumble into the abyss and are lost.

The beacon stops signalling, and the Doctor realizes that the TARDIS they’re detecting isn’t his. Frustrated by the Time Lords’ hesitation, the Doctor pushes past the Under-Cardinal and pilots the Time Station beneath the cloud cover before Vansell can stop him. Their descent scatters the ghosts before they can descend upon Charley and Levith, but the Doctor dismisses the forest of metal spikes as another sensor fault -- although he admits his mistake after the Station crashes. Vansell is concussed by the crash, and deliriously quotes from Gallifreyan mythology -- “Zagreus waits at the end of the world, for Zagreus is the end of the world; his time is the end of time and his moment time’s undoing.” The Doctor is puzzled; why does a make-believe villain from children’s stories keep reappearing today...?

Vansell is infuriated when he recovers, but as he threatens to erase the Doctor from history completely, Charley’s ghost materializes -- or rather, the spectre which has taken Charley’s form. The Doctor realizes that this is a native of the Antiverse, a Never-person -- and he’s horrified when it reveals that it has passed through the breach before, and that it consumed Lucy and Richard Martin while it was there. More Neverpeople materialize in the station and begin drawing temporal energy out of its cracked time rotor, but when Vansell tries to drive them off, their leader informs him that the thing he seeks lies in a grotto not far from here. Vansell decides to set off immediately, and though the Doctor questions the wisdom of leaving the Time Station to the Neverpeople; however, Romana reveals that if they leave the Station long enough it will repair itself. The Doctor reluctantly accompanies Romana, Vansell and the guards out of the Station, beginning to suspect that Romana hasn’t told him the whole truth about their visit to the Antiverse. He’s right, and Vansell fears that the Doctor will oppose them when he learns the truth...

Outside, the Doctor is reunited with Charley, and while Levith reports to Romana and Vansell, the Doctor studies the metal spikes; they are artificial, and the ground itself consists of iron filings. Acid begins to rain from the sky, and the Doctor, Charley and the Time Lords shelter in a nearby cave -- but as they head deeper into the cave they realize that the tunnel is more like an artificial corridor. Charley spots a familiar round pattern on the walls, and when they enter a vast chamber with a hexagonal structure at the centre, the Doctor realizes that this “planetoid” -- which must be from their own universe -- is the wreck of a TARDIS.

The Doctor isn’t convinced that Rassilon has really returned, but the circumstantial evidence fits together. Zagreus may be a character from a nursery rhyme, but as Charley points out, “ring-a-ring-a-rosies” is a nursery rhyme too, which came out of the truth of the Black Death. Vansell reveals that Zagreus appears in the legends of many other worlds, and that all of the legends have a common thread; a folk hero named Azalon, or Razlon, abandons his people to do battle with the monster Zagreus, but ensures that all records of his journey are destroyed for fear that the truth would undermine his utopia. Vansell is convinced that the tomb in the Death Zone is a sham -- Rassilon remains here, alive and suspended in the Antiverse, and what might the Time Lords achieve if he returns to Gallifrey?

The Neverperson with Charley’s form arrives and offers to negotiate the Time Cabinet’s return with Vansell. Romana is wary of the Neverpeople, but Vansell is no longer willing to stand by and simply observe while the opportunity to change the Universe for the better lies open. With the web of Time’s architect by their side, there is nothing they can’t achieve. Despite the Doctor and Romana’s wariness, Vansell listens to the Neverperson’s terms; they will return the Zero Cabinet in exchange for limited freedom to trawl the timestream for the temporal energies which give their lives meaning, and as a show of good faith, one of the Time Lords must remain in their realm. The Doctor protests that this will mean transforming Charley into a permanent open gateway, but Vansell ignores him and agrees to the Neverperson’s terms -- and, showing loyalty to the legacy of Rassilon rather than to an ephemeral President, he nominates Romana to stay behind. The Doctor realizes that, while Vansell may not have expected the presence of living beings in the Antiverse, this was probably his intention all along -- to pull off a bloodless coup, getting rid of Romana and returning to Gallifrey as Rassilon’s right-hand man.

Vansell’s loyal guards force the Doctor, Romana and Charley out onto the surface, where the earth splits open to reveal the Zero Cabinet. The Neverpeople transport Romana away, and the Doctor, standing too close to the edge, topples into the crevasse. Vansell lets him fall, and orders his guards to take Charley and the Cabinet back to the Time Station, rid at last of the meddling Doctor and Romana. The casket crackles with energy as Vansell places it on the bridge of the Station, intending to open it under controlled conditions back on Gallifrey. Charley is furious, but is helpless to resist as the guards bring the proton accelerator to the bridge...

Romana tries to keep her dignity as she is marched into an amphitheatre filled with thousands upon thousands of Neverpeople, all baying for her blood. Their spokesperson introduces Rorvan and Taris, two Neverpeople who claim to have been Romana’s best friends at Lake Abydos. Romana is bewildered; she did spend her summers at Lake Abydos, but she never had any friends there. The gloating Neverperson questions Romana about the Oubliette of Eternity, one of the darkest secrets of the CIA -- a chamber once used to disperse criminals found guilty of high treason, erasing them from the timelines completely, as if they had never existed. The Doctor arrives in time to hear this and to deduce the horrifying truth -- the Neverpeople are dissipated Time Lords, victims of the Oubliette. Rorvan and Taris were indeed Romana’s best friends -- or would have been, if not for the fact that they were caught accessing classified documents, and thus never existed in the first place...

The Neverpeople’s spokesperson, the one with Charley’s form, identifies herself as Sentris, the 217th Co-ordinator of the Celestial Intervention Agency. Like all Gallifreyans, she believed that dispersal was an abominable punishment, used only in the most extreme circumstances -- but one day she checked the records in a time-protected vault and learned the appalling truth. The Oubliette had “never” been used only because its victims never existed in the first place -- and Sentris had in fact approved the dispersal of over 200 people in less than a year. Unable to live with herself, Sentris cast herself into the Oubliette -- and ended up surrounded by her own victims, condemned to eternal non-existence in the universe of anti-Time, with no way out -- until the Doctor opened the dimensional breach by saving Charley. Sentris has taken the form of the breach as a flag of honour.

Romana vows that the Time Lords will remember this injustice -- but the enraged Sentris reveals that it still goes on. The Oubliette of Eternity is still in operation, and the ranks of the Neverpeople grow daily as Co-ordinator of the CIA continues to disperse victims in the name of his President. The Doctor realizes that the Neverpeople must hate Vansell as much as they do Romana -- and Sentris also blames Rassilon, whom he claims decreed that all who threaten the empire of Time should be expelled from it. The Doctor realizes the implications. Rassilon must have realized that anti-Time was simply a force of nature, not a bogeyman -- which means that the legends of Zagreus are false, a trap planted by the Neverpeople to lure the Time Lords out from behind the barriers they set up when the web of Time began to fray. Rassilon’s body really does lie in the Death Zone -- which means that the casket contains something else...

The Time Station is fully repaired and the time rotor is recharged. As Levith straps Charley into the proton accelerator, Charley tries to get through to her, reminding her that abandoning Romana is an act of treason -- and pointing out that Vansell seems to be talking to the casket. When Vansell speaks, they can hear a crackle in his voice, indicating that he has been infected by the energies of anti-Time. Rorvan and Taris arrive to observe the Station’s departure, and when Vansell welcomes them aboard even Levith realizes that something’s wrong -- but she’s left it too late. The anti-Time energy emanating from the casket has infected her as well, and she operates the proton accelerator, twisting Charley back into a dimensional gateway.

Sentris reveals that the casket on the Time Station contains a critical mass of raw anti-Time energy. Gallifrey has sealed itself off from the time distortion, but a Presidential station carrying the head of the Celestial Intervention Agency will be allowed through automatically. When the Station materializes, the casket will detonate, and the Capitol will be flooded with raw anti-Time, casting loose the web of Time’s last anchor and plunging the Universe into chaos -- the empire of Zagreus. Though the Doctor sympathizes with the Neverpeople’s fate, he will not allow Sentris to destroy the Universe -- but how can he stop her? The mock trial is over, and Sentris allows the Neverpeople to descend upon the Doctor and Romana, to fill themselves to bursting with the Time of their lives...

However, a fault develops in the Time Station, which stalls during materialization. Sentris is forced to call off the Neverpeople and return the Doctor’s TARDIS; as the Neverpeople remain incorporeal, they are unable to repair the Station themselves, and none of the possessed Time Lords aboard have the requisite knowledge. The Doctor agrees to return to the Station, and Sentris boards the TARDIS with Romana as a hostage to ensure his good behaviour. Romana has a plan, however, and she manages to tell the Doctor; if she can get to the Matrix chamber on the station, the one the Doctor was in earlier, she can change her Presidential authorization codes and prevent the Station from materializing on Gallifrey. The trick will be getting her there.

The TARDIS materializes on the Time Station’s bridge, where Charley is recovering from her ordeal -- and the entire crew is infected with anti-Time energy. Vansell is dimly aware that something is wrong, but he refuses to abandon his mission. The Doctor studies the damage and tells Romana to reset the flux patterns in the reactor while he works on the bridge; however, Vansell doesn’t trust either of them, and advises sending an escort with Romana. Sentris sends Vansell himself, along with Rorvan and Taris; before they leave, the Doctor gives Romana his sonic screwdriver in case of emergency. He then links the Station’s controls to the TARDIS to boost power to the time rotor... and is then forced to wire the casket to the Station’s self-destruct system when Sentris orders Levith to shoot herself in the head if he disobeys. When the Time Station materializes on Gallifrey, it will self-destruct as the casket opens, spreading anti-Time fallout over the whole of the planet before the Time Lords know what’s happening...

Rorvan and Taris’ presence ensures that Vansell won’t listen to Romana’s story, but she refuses to waste what little time she has left convincing them that bitterness has warped their reasoning. Once they reach the temporal reactors, however, the positive temporal energy draws Rorvan and Taris towards it like moths to a flame, and Vansell, now far enough away from the casket, regains control over himself and realizes to his horror what he’s done. Romana explains her plan; first, however, she needs to get rid of Rorvan and Taris by lowering the blast shutters and raising the force shield, exposing them to the full power of the reactor core. Vansell and Romana cross to the two shutters, but the one on Vansell’s side jams open -- and although he is still exposed to the core, he raises the force shield before Rorvan and Taris can escape, sacrificing himself to destroy them and give Romana the time she needs.

The power surge brings the Station’s time rotor back on line, but Sentris feels Rorvan and Taris’ loss and realizes what Romana intends to do. The possessed Time Lords lower the ship’s emergency bulkheads to block her out of the Matrix chamber, but thanks to the Doctor’s sonic screwdriver, she gets through and into the Matrix. This does her no good whatsoever, for all of the voices in the Matrix are now mad, babbling nonsense about Zagreus and the end of days, and she can’t get anyone to listen to her long enough to change her authorization code. On the bridge of the Time Station, Sentris reveals to the Doctor that the plan was doomed to failure anyway; before leaving on this mission, Vansell ratified a new order making it impossible to amend authorization codes during a state of emergency. The Doctor tries to remain optimistic, but Sentris knows there’s only one sure way to prevent the disaster to come -- and she is vicious enough to offer the Doctor the opportunity, knowing that he’ll turn it down. Charley knows exactly what they’re talking about -- they can’t get through the breach if the breach no longer exists...

Amused, Sentris orders Levith to give the Doctor her gun. Charley insists that she’s accepted her fate, and that she doesn’t regret a moment of the time she’s spent with him. She’s seen more wonders and miracles than she’d ever dreamed possible, and if the web of Time falls apart then none of those things will ever have existed. She is ready to die to save the Universe -- but the Doctor can’t bring himself to kill his friend, whatever the cost. Sentris, triumphant, orders Levith to activate the proton accelerator, and Charley, bitterly disappointed with the Doctor, is twisted once more into the shape of the space/time gateway. The Doctor, enraged, reminds Sentris that she condemned herself to oblivion out of guilt over the murder of innocents; yet now she’s willing to destroy the web of Time and unmake the lives of millions. But bitterness and hatred have warped Sentris’ mind, and she won’t listen to reason. The Station dematerializes, heading for the breach and thence Gallifrey, but the Doctor realizes that there’s still one course of action open to him. Before anyone can stop him, he leaps into the TARDIS and dematerializes. Sentris allows him to go; nothing can stop the Station from materializing on Gallifrey now...

The Doctor approaches the breach, desperately reconfiguring the TARDIS’ superstructure -- but as he works, time and space come to a halt, and a very familiar presence appears. This is the old man whom the Doctor saw in the Matrix, whom Sentris impersonated back in the Antiverse -- and he has halted Time at this, the most crucial moment in the Doctor’s life, so the Doctor can explain what has led him to this. Confused, but accepting that there’s time enough to tell his story, the Doctor does so, beginning with the R101 and his first meeting with Charlotte Pollard, continuing through their adventure with Sebastian Grayle and ending here, with the Doctor poised to save Gallifrey -- regardless of the consequences to himself. The old man gently asks the Doctor if he has considered every possible alternative, and when the Doctor assures him that he has, the old man steps aside. He will allow the Doctor to make his own decisions and face the consequences, but before the end comes he wants the Doctor to know one thing -- he has watched the Doctor through all his lives, and the Doctor has made him proud. Time begins to flow forward again, and the Doctor, unsure what’s just happened, returns to work...

The Time Station passes through the breach and materializes on Gallifrey, and Levith initiates the self-destruct sequence. But as Sentris crows over her victory, it’s snatched from her grasp -- as the Doctor’s TARDIS materializes around the entire Station. There’s no way for Sentris to stop the countdown now; the TARDIS will hold in the explosion, containing all of the anti-Time fallout until the Time Lords can deal with it. And although the Doctor knows this trick will cost him his life, he’ll have spent it to save the Universe and his friend. Sentris shrieks in fury as the countdown reaches zero -- and the Time Station explodes.

Romana is surprised when the madness in the Matrix suddenly returns to normal. The data recorders are now perfectly sane, and history makes sense again -- including Charley’s rescue, the resulting anti-Time incursion, and the Doctor’s self-sacrifice. The wise old man appears before Romana, confirming that the threat to history has now become a part of history itself... and that although the price the Doctor paid was terrible indeed, Charley is now safe. Since the breach is now a fact of history, so is her survival, and her existence is no longer a paradox. The old man then gives Romana the opportunity to return to Gallifrey -- but if she chooses to do so she cannot be told what the future holds. All she can know is that Charley still has a part of play in the next chapter of Gallifrey’s history -- and a dark and terrible chapter it will be. Disturbed, Romana chooses to play her own role in history, and steps out of the Matrix. The old man watches her go, sadly, knowing what she will soon face. For Zagreus waits at the end of the world, and Zagreus is the end of the world; his time is the end of Time, and his moment Time’s undoing...