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.

Two brothers, both cadets at Annapolis, fall in love with the same girl.

The first of the five films where Bill Elliott played a detective lieutenant in the L.A Sheriff's department, Dial Red "O" (the correct title with the number 0 (zero), as on a telephone dial, shown in ") opens with war-torn veteran Ralph Wyatt getting word that his wife is divorcing him, and he flees the psychiatric ward of the veteran's hospital, wanting to talk to her. His escape touches off an all-out manhunt, led by Lieutenant Andy Flynn of the sheriff's department.