Continuity: The ominous tolling bell is presumably a cloister bell, the TARDIS emergency signal that first appeared in the Doctor Who episode Logopolis and has been heard on numerous occasions since.

Continuity: Jess Carter, the socially inept student introduced in Welcome to the Machine, is said to have committed suicide in this story. Nryn was introduced in There Need Never Be Longing in Your Eyes. See also the final story, After Life.

Continuity: This story introduces a new character: Dr Wt'hlm, an entity of pure thought who interacts with the world through a humanoid robot. Jess Carter also commits suicide in this version of history (see the notes for Siege Mentality).

Benny awakens in hospital to learn that Doggles’ history machine exploded, releasing a strange form of temporal radiation. Several people have been killed, Benny has been permanently blinded -- and Peter has been mortally injured and will be dead within days. Adrian ends his relationship with Bev to concentrate on his family, and the furious Bev prepares to pack up and leave the Collection, where everyone seems to idolise Benny when Bev has done so much more for them. But Benny contacts her and asks for her help: she needs to contact Avril Fenman and fetch one of the sorceress’ mind-swapping crystals so she can trade places with Peter. When Jason arrives at the hospital, Bev is just leaving, and when Jason learns what Benny has done, he realises why she asked Bev. She claims that Bev is the only person who disliked her enough to let her trade her life for Peter’s, but Jason realises that Benny knew that Avril had been trapped in a man’s body for too long -- and that it wasn’t really Bev whom Jason bumped into in the corridor outside. Furious, Jason storms out of the hospital room to take care of matters, but when Benny tries to pick up the crystal, she discovers too late that Adrian had been nearby, listening -- and he’s already taken the crystal to Peter’s room. Benny is too late to stop Adrian from sacrificing his life for his son’s, and she vows to track down Avril and make her pay for what she’s done to them all -- but she knows that it’s her own fault for trying to take on the responsibility herself.

Benny tries to cross the lawn and unplug the history machine before it explodes, but it’s causing her to relive events from her past. She is a teenager at the military academy, paired up with young Lucy Amandla; all of her efforts to whip Lucy into shape fail, and when she realises that Lucy genuinely believes that she’s cannon fodder and that her death would make no difference, Benny goes AWOL and lives alone in the woods for the next two years. Lucy later whips herself into shape and dies in battle on Solidad, holding off the enemy while the planet’s civilian population escapes to safety. Later in Benny’s life, as a young archaeologist with fake credentials, she tries to find evidence that the cute and cuddly natives of the second planet of Hib 34598 have the potential to develop an advanced civilisation and therefore must not be exploited by the galactic corporations. Instead, she finds evidence that they are the descendants of a militant faction from another planet, who settled down in a deliberately primitive lifestyle after invading this world and slaughtering its true natives. Even later, she returns to her home on the Braxiatel Collection to find that it has been invaded by the Fifth Axis, and her world comes to an end when she’s told that her son Peter is dead. Finally, she unplugs the history machine, and restores everything to normal... only to realise that everyone at the press conference has shared these personal and private experiences with her.

Continuity: Benny refers to archaeological work being conducted on Vulcan, presumably the planet from Power of the Daleks.

Shortly after testing a new pesticide in his gardens, Hass helps a group of Killorans to move the Crystal of Lexam, a legendary Martian artefact said to contain the spirit of a great warrior named Vorzz. That night, Hass dreams of the death of Vorzz, and, as if possessed, walks into the Collection to touch the Crystal again, nearly killing Bev Tarrant in the process. He is overpowered by the Killorans and by Bev, who survived his attack. Three days in the hospital enable him to shake off the influence of the Crystal, which may have been magnified by the effect of the pesticide on his brain. He and Bev agree that the Martian artefacts should probably be returned to Sset, but they also feel that Braxiatel is concentrating on his feud with the Martians in order to forget his own sense of loss, since Benny was killed when the history machine exploded.

Both Jason and Adrian are killed when the history machine explodes, and the shockwave devastates the civilised galaxy. In the aftermath, a movement called the Enlightenment begins to sweep across the galaxy, slaughtering human beings en masse for no apparent reason. Benny and Bev both join the resistance, fighting Enlightenment troops wherever they are found, but while Bev has lost herself in the need to fight, Benny still struggles with her conscience when it comes to killing. On the planet Petrocia, she tries to surrender when it becomes clear that her troops are outnumbered, but Bev opens fire on the advancing Enlightenment forces, leaving Benny with no choice but to detonate the Resistance’s atomic weapons and kill a quarter of a million enemy soldiers. Eventually, however, she and Bev are captured -- and although Bev is taken away to be executed, Benny is allowed to live after her DNA analysis produces some surprising results. An agent of the Enlightenment explains that their scientists have isolated the genes that enable a human being to empathise with others and transcend the limits of their animal nature. As far as the Enlightenment are concerned, humans without the sapience gene are chaff with no comprehension of the true value of human life, and they’re holding back the evolution of the human race -- and to Benny’s horror, the Enlightenment don’t believe that they need to brainwash her to accept their ideals, because according to her DNA analysis, she is already one of them.

Jason is permanently disfigured by a facial scar when the history machine explodes, and comes to fear that Benny may no longer love him as she used to. Unable to express his feelings for her, he asks Hass for help, and Hass eventually agrees to help him transform part of the gardens into a love letter. Through careful floral arrangement -- the Martian art of “writing in green” -- Hass spells out a message of love in scent and colour, so successfully that after Jason shows it to Benny, she becomes pregnant with a girl. However, she recognises Hass’ hand in the gardening, and eventually he admits that as a personal touch, he buried a Martian time capsule, a stasis bubble that exists outside Time and contains the voices of those he has known in the Collection. After he digs it up and it tells its story, Hass admits to Benny that the Collection no longer feels right to him; however, before tendering his resignation, he suggests that Benny name her new child Acacia, after the flowers in Jason’s love letter. Or at least, this is the story that the time capsule tells, but it’s wrong; Jason never came to Hass for help, and Benny is not pregnant. Hass destroys the capsule, realising that since its story was preserved outside Time, somehow Time itself has changed since he buried it...

A young man named Paul Stevens applies for a job at the Braxiatel Collection, which is in a state of confusion following the explosion of the history machine. Many of the artefacts in the Collection have been misfiled or lost, and the scarred Jason Kane -- who appears to be in charge, since neither Braxiatel nor Benny are available -- warns Paul that some of the artefacts may be dangerous. While organising the inventory in his section of the Archaeology Department, Paul discovers that a certain statue has gone missing, and when he reports this to Bev Tarrant, she warns him that he’ll have a lot to worry about if it isn’t located. Fearing that his job is at stake, Paul makes an extra effort to locate the statue, and to his surprise, the rooms in this part of the Collection seem to reconfigure themselves around him as he does so. The reconfiguration opens up a large cavern where he finds the statue connected to the wall by a wire, its eyes glowing a terrible bright green. Paul simply unplugs the statue and returns it to Jason and Bev, telling them that he’s worked out the truth; the Collection would never be so careless as to lose a truly dangerous artefact, and this has all been an initiative test to judge his ability to do the job properly. Jason and Bev decide that it would probably be best to let Paul keep believing that.

The history machine functions flawlessly, as the glaring white glow is revealed to be the Big Bang; nevertheless, Benny feels that something has gone very wrong. Braxiatel arranges for Doggles to be sequestered in private quarters to give him a break from the media attention, but Benny gets in to visit him, fearing what might happen should the history machine get out onto the open market. Unfortunately, this means that she’s the last person to see him before Braxiatel announces that Doggles has been found beaten to death. The history machine has also been destroyed, which means that they can’t use it to watch the murder -- and since Adrian’s new security protocols are in place, only a member of staff could have been able to commit the crime. Benny is the prime suspect, since the guards heard her arguing with Doggles before she left. Bev tells Benny that she was with Adrian at the time of the murder, but Adrian inadvertently contradicts her later, and Joseph then catches Bev stealing Benny’s diary from her rooms. When Braxiatel assembles the suspects together, Benny points out these discrepancies in Bev’s behaviour, but Braxiatel reveals that Bev lied about her whereabouts because she was in fact carrying out a secret errand for him. Benny’s diary entries don’t mention her argument with Doggles, she has only been able to defend herself by throwing suspicion on Bev -- and Braxiatel reveals that Doggles in fact survived his injuries, and has now come out of his coma and identified Benny as his assailant. Benny insists that Doggles’ history machine would have destroyed their understanding of history and the concept of personal privacy, but the others realise that she was in fact driven by a fear that archaeology would become a redundant discipline and that she’d lose her job. Braxiatel has no choice but to turn her over to the Interplanetary Police -- but Hass attacks Braxiatel to protect her, since Benny was his first and only friend on the Collection. Bev is forced to shoot and kill Hass to save Braxiatel’s life, leaving Benny to bear the guilt for his unnecessary death.

Continuity: Though he remains unnamed, the "friend" who gave Jason the thingy was probably the Doctor.

Benny wakes to find herself lying next to the damaged history machine with no memory of the past three weeks. Jess Carter is an outgoing party animal rather than an introverted loner; Mr. Crofton is tending the gardens; and Benny’s cat Wolsey is dead. When Benny unthinkingly asks Adrian Wall about his son, it takes four Killorans to hold the angry Adrian back; he and Bev nearly had a child together, but Bev miscarried. The gardener tends to Bernice’s wounds, but the gardener is Hass, not Mr. Crofton -- and when she asks about Braxiatel, he doesn’t seem to know who she’s talking about. Benny visits the Mansionhouse, but finds it locked and is forced to break in -- using a Fifth Axis gun inscribed with the name “Joseph” that she finds in her hip holster. Inside, she finds two versions of Braxiatel playing chess; the apparently older one is trying to convince his younger self to build a bomb that will destroy this entire version of reality, slowing the spread of the alternatives long enough for him to resolve the situation. Convinced that the real Braxiatel would never sacrifice his Collection for any reason, Benny shoots the older version dead. “Her” version of Braxiatel then hypnotises her, smoothes over the confused and contradictory memories in her mind, and sends her back home while he tries to formulate his own plan to save everything...

Continuity: Benny's gun is a Brimmicombe .45, which may have some connection to the family of the UNIT officer from Sympathy for the Devil and the UNIT audios. When she realises that there are aliens in the Collection, she hopes that she isn't up against a yeti, presumably a reference to The Abominable Snowmen.

Meanwhile, the “real” Braxiatel has been shifting between realities, trying to find a way to stop the fracture from spreading. While attending Benny and Doggles’ wedding in one version of history, he learns from Benny that Doggles feels that the technology implanted in his body by the Fifth Axis somehow drove him to create the history machine. Braxiatel thus realises what must be done. The detonation of the reality bombs in the neighbouring timelines slows the spread and creates a temporary stable pocket of Time in the gardens, giving Braxiatel just enough time to explain what’s gone wrong. The Collection’s new defences are an extension of Braxiatel’s time machine; in effect, the entire Collection has been removed from space and time and exists in its own pocket universe, and the history machine is interacting with that bubble of history, causing its reality to fracture. The effect is spreading out into the real Universe; already, the Martian Hass has become human. They have only minutes, maybe less, to stop the spread before this stable moment passes and all of space and time is destroyed -- and the quickest way to do that is to sever the machine’s link with the technology in Doggles’ body. Doggles panics and begs for his life; although Braxiatel insists that Doggles will survive when history resets itself, Doggles knows that he isn’t really so sure. However, the assembled guests are starting remember fragments of the different timelines they’ve shuffled through, and are too terrified of letting this happen again to protest; Benny in particular remembers committing mass slaughter as a soldier, and being told that her son Peter was dead, and despite her reluctance she stands by and does nothing as Hass drags Doggles to the stage and Braxiatel cuts off the screaming Cahlian’s head...

Benny’s cat Wolsey has died, and nobody except Benny and Hass attends the funeral in the Collection’s garden... at first. But as the funeral proceeds, people begin arriving, driven by some sense of loss and confusion. Something weird has just happened on the Collection; Jess Carter and Nryn have died for no apparent reason, and the time-travellers such as Benny and Bev find that they can vaguely remember things that didn’t actually happen. Benny is subsequently surprised when Braxiatel refers to Hass as a Martian, for Hass is -- and always has been -- a Yesodi, a jellyfish-like alien in a pressurised metal suit. Braxiatel advises Benny not to push for an explanation, and tells her that a Cahlian named Doggles is on his way -- but he can’t be allowed to activate his history machine on the Collection, for fear that it could cause feedback in the security systems. Benny and Bev settle their differences, as they’re both vaguely aware that they’ve done terrible things to each other. Jason tells Benny that, although he loves her, he’s willing to let her go if she finds someone better, but she firmly tells him not to think like that. Nevertheless, when Doggles arrives, Benny finds herself warming up to the newcomer...