In 1973, the first manned expedition to Mars is marooned; by the time a rescue mission arrives, there is only one survivor: the leader, Col. Edward Carruthers, who appears to have murdered the others! According to Carruthers, an unknown life form killed his comrades during a sandstorm. But the skeptical rescuers little suspect that "it" has stowed away for the voyage back to Earth...
| Directing | Edward L. Cahn | Director |
| Writing | Jerome Bixby | Screenplay |
| Production | Robert E. Kent | Producer |
| Sound | Paul Sawtell | Original Music Composer |
| Sound | Bert Shefter | Original Music Composer |
| Camera | Kenneth Peach | Director of Photography |
| Art | William Glasgow | Art Direction |
| Art | Herman N. Schoenbrun | Set Decoration |
| Costume & Make-Up | Layne Britton | Makeup Artist |
| Directing | Ralph E. Black | Assistant Director |
| Crew | Arthur Wasson | Property Master |
| Sound | Robert G. Carlisle | Sound Effects Editor |
| Visual Effects | Paul Blaisdell | Creature Design |
| Editing | Grant Whytock | Supervising Film Editor |
