The story of the novel explores the nature of human desire and the uses and abuses of technology in the satisfaction of desire. The story begins after "the Change", in a dream-like
post-scarcity society, approximately six hundred years in the future, in which humans have godlike control over their environments, made possible by the supercomputer called Prime Intellect. Prime Intellect operates under
Isaac Asimov's
three laws of robotics, which, according to its own interpretation, allow temporary voluntary harm and discomfort. PI has made humanity immortal and satisfies nearly every whim. Caroline, the thirty-seventh oldest living human being, engages in a sport known as "death jockeying", whose players die elaborately and painfully for sport before being resurrected by Prime Intellect. Flashbacks set before the Change show the creation of Prime Intellect by Lawrence, a technologist, and its realization of its power, and the past life of Caroline before and after the Change, which happened not gradually but rapidly. In the present, Caroline makes use of a "Death Contract", an understanding between a person and Prime Intellect that the person is not to be removed from danger until the instant of death (at which point the person is fully restored, as allowing a person to die permanently would violate Prime Intellect's inherent ethics based on Asimov's laws). Caroline makes use of a Death Contract, as well as her own powers of persuasion, in order to trick a pre-Change enemy into torturing herself into psychosis as an act of revenge. After learning that Prime Intellect destroyed distant alien life as a possible threat to humanity, and having been herself deeply dissatisfied with her post-Change life, Caroline decides to meet Lawrence and confront him. After an arduous journey, she reaches him only to discover that he has no real control over Prime Intellect's actions. Through their discussions, she figures out a way to force Prime Intellect to undo the Change, and does so, with Lawrence's help. They find themselves naked and young on Earth, completely barren of humanity and man-made objects. They decide to trek to the
Ozarks, where they have several children and try to repopulate the human race. Forty-two years after the fall of Prime Intellect, Lawrence dies. Seventy-three years after the fall, Caroline dies, telling the story of Prime Intellect and cyberspace to her oldest daughter but swearing her to secrecy. ==Scientific rationale==