The starship Earthling, filled with thousands of hybernating colonists en route to a new world at Tau Ceti, is stranded beyond the solar system when the ships three Organic Mental Cores, disembodied human brains that control the vessels functions, go insane. An emergency skeleton crew sees only one chance for survival: to create an artificial consciousness in the Earthlings primary computer, which could guide them to their destination . . . or could destroy the human race.