American astronaut Frank Douglas mysteriously disappears from his spacecraft as it parachutes to Earth. He is apparently replaced by or turned into a large, radioactive, humanoid monster. A team of scientists and military men attempt to capture the monster.
| Writing | Dok Stanford | Screenplay |
| Writing | Bill Rebane | Screenplay |
| Writing | Jeff Smith | Screenplay |
| Directing | Herschell Gordon Lewis | Director |
| Production | Bill Rebane | Producer |
| Directing | Bill Rebane | Director |
| Production | Herschell Gordon Lewis | Producer |
| Crew | Herschell Gordon Lewis | Additional Dialogue |
| Camera | Frank Pfeiffer | Director of Photography |
| Costume & Make-Up | Lillian Toth | Makeup Artist |
| Art | Herschell Gordon Lewis | Production Design |
