Jerome Branch Corbell has incurable cancer, so he has himself
cryogenically frozen in 1970 in the faint hope of a future cure. He is revived in 2190 by a totalitarian global government called "
the State". His personality and memories are extracted (destroying his body in the process) and transferred into the body of a
mindwiped criminal. After awakening, he is continually evaluated by Pierce, a "checker" who has to decide whether he is worth keeping. With the threat of his own mindwiping looming, Corbell works hard to pass various tests. Pierce concludes that Corbell is a loner and born tourist, making him an ideal candidate to pilot a one-man
Bussard ramjet, seeding suitable planets as the first step to
terraforming them. Figuring out it is a one-way trip and disgusted with the State's treatment of him as an expendable commodity, Corbell hijacks the ship after its launch and decides to visit the
center of the
galaxy instead. (It was at this point that the original short story ended.) Pierce (actually named Peerssa) cannot talk him out of it. Through subterfuge, an
artificial intelligence (AI) program based on Peerssa's personality is secretly beamed into the ship's computer. Though the Peerssa AI opposes the detour, it cannot disobey Corbell's direct orders. After a lengthy journey, made possible only by Corbell undergoing
suspended animation, he returns to the
Solar System. Only about 150 years have passed on the ship, but three million years have elapsed on Earth due to extreme
time dilation. Viewing him as a potential threat to the State, Peerssa did not offer a different route home which would have returned him to an Earth only seventy thousand years older, when the State might possibly still have existed. At first, Corbell wonders if he is in the wrong system because it has changed considerably; the star is a
red giant and what might be Earth is in orbit around what could be a much hotter
Jupiter. Having followed a message clearly from humans (warning not to visit other human-occupied star systems), and being too old to survive going anywhere else, Corbell puts the ship into orbit around what turns out to be Earth. The climate has changed, especially the surface temperature; the poles are now
temperate, while the former
temperate zones reach temperatures of over 50 degrees Celsius (120+ degrees Fahrenheit). The poles also experience six years of night and six of day. Almost all remaining life has adapted to live in Antarctica, except for some indications of biological activity in the Himalayan mountains. When Corbell lands (in a modified biological probe), he is captured by Mirelly-Lyra, who is a fellow returned starship crewperson and refugee from the past — though from Corbell's future. She explains that the human species has fragmented; it is dominated by a race of immortal, permanently pre-adolescent males (the Boys). Sometime in the past, they had defeated the equally immortal (though now extinct) Girls in the ultimate war of the sexes. The Boys have enslaved the
dikta, unmodified humans (though they have evolved somewhat), from whom they take boys to replenish their ranks. Mirelly-Lyra had initially been a captive toy of the Girls. After their downfall, she obsessively searched in vain for the lost adult-immortality treatment, extending her life as much as possible using her own anti-aging drugs and a form of
zero-time stasis, while waiting for another returning starship and potential help. Because she could not stop the aging process entirely, she is an old crone by the time she captures Corbell. He manages to escape from her, only to be caught by the Boys, who take him to a
dikta settlement. Corbell finds out that the Girls moved the Earth to a habitable distance from the Sun, made much more energetic by a breakaway interstellar colony in its war with the State, but an error caused Jupiter to overheat. In desperation, the Girls tried to take over the Boys' territory to save themselves, but lost. With Gording, the
dikta leader, Corbell escapes once more. Eventually, Corbell discovers the adult-immortality treatment by accident, only realizing it after he shows signs of rejuvenation. He uses it to enlist Mirelly-Lyra's help, which in turn gives him control of his ship. (Peerssa has decided that Mirelly-Lyra is the last survivor of the State and will obey only her.) Peerssa maneuvers the planet
Uranus (previously used by the Girls to move the Earth using its
gravitational attraction) to drag Earth into a new orbit further from Jupiter to lower the temperature without killing the plants and animals that have adapted to the extreme conditions. He figures out a way to liberate the
dikta and enable them to regain control of their own destiny and repopulate the world. == Literary significance and reception ==