Harve and Helen, married scientists, part ways before Harve embarks on an eight-year interstellar mission; due to relativistic time dilation, what feels like eight years for him will amount to a century on Earth.

On returning in 2129, Harve is shocked to find Earth vastly transformed—desolate regions, depopulated areas, and societies changed beyond recognition.

He looks forward to reuniting with Helen but learns that her own work led to ground breaking—and unsettling—changes.