Four astronauts returning from man's first mission to Mars enter a time warp and crash on a 26th Century Earth devastated by atomic war. At first unaware where they are, but finding the atmosphere safe to breathe, they start exploring and find themselves in a divided future where disfigured mutants living like cavemen inhabit the surface, while the normals live comfortably below the surface but are dying as a race from lack of natural water, air and sunlight.
Hugh Marlowe
Nancy Gates
Rod Taylor
Lisa Montell
Nelson Leigh
Christopher Dark
Everett Glass
Booth Colman
Shirley Patterson
Stanley Fraser
William Vedder
Mickey Simpson
Keith Richards
Michael Garth
Nancy Howard
Mimi Gibson
Hugh Corcoran
David Alpert
John Close
Walter Conrad
Don Kennedy
Herb Vigran
John Hiestand
William Forman
John Bleifer
Rankin Mansfield
Strother Martin
Paul Brinegar