"CinemaScope's first science-fiction thriller" sees four intrepid astronauts (Hugh Marlowe, Nelson Leigh, Rod Taylor and Christopher Dark) successfully complete mankind's first Mars mission, only to run afoul of a warp in space. Tossed centuries into the future, they discover an Earth devastated by nuclear war, where mutant beast-men rule the surface. Underground is a society marked by listless males and lustful ladies (future- wear designed by Vargas!). Trapped in a tomorrow they never made, the four astronauts take on the mutant and the malicious while fighting to bring humanity back to the surface.