Astronaut Neil Stryker (Glenn Corbett) returns from space, only to find himself held incommunicado by government security people he's never seen before, in a hospital facility that he's never heard of. He escapes from the hospital… More Astronaut Neil Stryker (Glenn Corbett) returns from space, only to find himself held incommunicado by government security people he's never seen before, in a hospital facility that he's never heard of. He escapes from the hospital and, to his shock, sees a night sky lit up by three moons. He now knows that he's not on Earth -- but on some sort of near-duplicate of Earth, a parallel planet. He learns that the planet is called Terra by its inhabitants; and it resembles Earth in gravity, atmosphere, and environment -- it could pass for Earth, and the place where he is stranded might pass for any northeastern American city; but this world is ruled by a totalitarian government called The Perfect Order, which regiments day-to-day life on a level that would make even the worst Communist regime seem like amateurs; and it is ever on the lookout for unbelievers, non-conformists, subversives, and potential sources of contamination -- of which Stryker is a prime example, as someone from another world. Security agent George Benedict (Cameron Mitchell) is on his trail, and quite prepared to prevent any "contamination" that Stryker leaves behind along the way, even sending the rather high-ranking physician (Tim O'Connor) who spent time interrogating Stryker to the dreaded "Ward E," where his memory, free-will, and reasoning ability are cleaned and reshaped. Stryker quickly discovers that it's virtually impossible to trust anybody, because almost 100% of the population is in the Perfect Order's hold. He manages to find an ally in a young doctor (Sharon Acker), who enlists the help of her free-thinking mentor (Lew Ayres) on Stryker's behalf. But his only hope of true escape is to reach the government's launch facility, commandeer a spacecraft, and try to return to Earth.