A terrorist creates a biological weapon in an abandoned undersea lab. A government operative is dispatched to confiscate the weapon and eliminate the terrorist. This lone Navy SEAL must undertake a dangerous underwater mission to stop a madman from unleashing a deadly toxin that could destroy the world.

On its way back to Earth, the space shuttle Nautilus passes through a cloud of alien spores causing its sole occupant, astronaut Steve Thomas to transform into a blood-thirsty monster. The shuttle crashes into a swampy region of central Florida, creating a situation which threatens contagion and/or death to all who encounter the shuttle or its mutated pilot.

After a lengthy space mission, two astronauts (Steve Barkett and Larry Latham) return to an Earth transformed by nuclear war. As renegade gangs and mutants rule Los Angeles, the astronauts join two pretty women and a couple of kids in a growing resistance movement. This sci-fi adventure follows the men as they battle bell-bottomed biker leader Cutter and his brutal gang.