Benny is supplying herself with extra money by baby-sitting a group of spoiled rich children on a quasi-archaeological field trip to the planet Malanoor, when she is contacted by her old friend Sgloomi Po the Sloathe. Sgloomi has already collected Chris, who explains to Benny that something from outside the normal parameters of time and space is eliminating the alternative Universes that arise whenever quantum possibilities diverge from one another, and that the resulting fractured Universes are whipsawing through our own, threatening the collapse of all timelines into total oblivion. The nexus of the possibility disruption is on Earth, where the former crew of the Schirron Dream -- Nathan li Shao, Leetha t'Zhan, and Kiru -- are trapped, flipping from one alternative to the next and failing to hold onto a sense of their own identities in the process.

Sgloomi has also picked up Jason, on the assumption that humans mate for life and Benny and Jason would wish to spend the end of the Universe together, and it's somewhat taken aback at the vitriol with which they greet each other. Nevertheless, the expedition sets off, and Sgloomi takes the Schirron Dream to pick up the last remaining member of the expedition. Somehow, the ship passes into a different probability line while doing so, and Chris and Benny are appalled when Sgloomi returns to the ship with a panic-stricken, much younger, and definitely not dead Roz Forrester. Chris tries to explain the situation to her as best he can, while the ship approaches Earth; but it passes through another probability wavefront as it does so, and the crew suddenly find themselves facing armed marauders from the outer limits of the Solar System while Roz is transformed into a vicious Space Marine who's willing to kamikaze-strafe the enemy ships in order to save the Earth. Benny is surprised when Jason unexpectedly demonstrates a grasp of highly trained martial arts maneouvres in order to immobilise Roz until they've passed into another probability. Roz begins to lose her grasp on her identity and long-term memories as the ship passes through probability wavefronts, but Chris and Sgloomi help her to hold on to what's important; she has friends in danger and must help them.

The ship eventually lands on what's left of Earth, where it locates Nathan, Leetha and Kiru. After passing through alternative Earths and experiencing the same quest in the style of a film noir epic, a Holmesian mystery and a futile rebellion against an Orwellian totalitarian government, the three travellers have finally remembered who they really are and have been able to hold onto a sense of their identities despite the severe fluctuations to reality occurring around them. In every reality, however, one thing has remained constant; their mysterious enemy has been a man named Simon Deed. When the Schirron Dream lands, Simon Deed appears to them all in the form of a vast omnipotent Godbeing, who scorns these lesser beings who rebel against him, and blasts them into oblivion.

Except that doesn't happen. In fact, Roz remains conscious throughout the entire "death" experience and realizes that her companions have just been stunned by a galvanistic discharge, and then taken from their ship into a mysterious hangar by men in radiation suits. Sgloomi escapes due to the kidnappers' inability to come to terms with his polymorphic nature, and he manages to free Roz and they set off to find out what's really going on. They are quickly captured and brought before the man responsible; Randolph Bane, an extremely old, borderline (on the other side of the border) senile, and unbelievably rich man, who has been experimenting with an alien Egg he found in the archives of an organisation known as the Shadow Directory. With the Egg he can change the Universe, but only by using the mental energy of people displaced in Time, people who have no sense of their own identity.

After brainwashing one of his own minor employees, Simon Deed, Bane used Deed to set a trap for any travellers who might happen across the Earth, and then used them to set a trap for even more of the "Living Material" he required for his experiment. The Universe is not in fact on the point of collapse (yet); Bane was transmitting false mental images to the people he required in order to lure them to Earth. The process didn't work on Roz because she comes from a different probability line than the others. Roz's companions have been hooked up to virtual reality software connected to the Egg, and are living alternate lives corresponding to their own ideas of Hell. Jason is living a life as a down-and-out wife-beater sentenced to life imprisonment for beating his ex-wife until she miscarried; Chris is an Adjudicator who succumbed to temptation and bribes and became wholly corrupt; the army's attempt to brainwash Benny into obedience succeeded and she became a concentration camp commandant directly responsible for the deaths of tens of millions of sentient beings. Once their sense of self crumbles under the strain of their experiences, they will become empty slates receptive to the power of the Egg, and Bane will be able to use it to change the physical laws of the Universe itself, and thus ensure that he will never die. The fact that this means oblivion for every other sentient being in the Universe is irrelevant to him.