The year is 2360. A select group of a half million humans, the only survivors of global warming and the "Race Wars", are living a Spartan lifestyle and exhibiting loss of memory and emotions resulting from mind-altering drugs created by world leaders known as the Orchestrators. The drugs markedly slowed metabolism and aging, making them ideal for prolonging the lives of humans requiring long periods of travel in space. Henry Shannon is being groomed as the next Orchestrator who will lead a mission to Jupiter, hoping to find an inhabitable moon that can accommodate the humans remaining on Earth. After discovering that the moons of Jupiter are uninhabitable, Henry reluctantly agrees to return to Earth, ultimately bolstered by news that global warming somehow has given way to global cooling. During the return trip home, his wife is killed when an asteroid collides with their spaceship. Depressed and increasingly concerned about survival of the human race, Henry presses on and successfully lands his group back on Earth, which bears little resemblance to the planet they remembered. The returning passengers encounter strange new animal species and are stunned to find that Earth has been repopulated by a group of humans previously known as Tunnel People because of their subterranean lifestyle. Their Supreme Leader, Lillian Goodman, a long-time opponent of the Orchestrators, somehow alters the Tunnel People who now have advanced technologies, an above-ground life of opulence, and apparent immortality. As Henry unravels the nefarious means employed by the Supreme Leader to create this Utopian state, he discovers why these new humans remain desperately dependent on his passengers for maintaining their immortal status, and must decide whether to cooperate or resist and face his own mortality.