On Jupiter's moon Ganymede, an alien life-form has taken over the body of a human astronaut, creating an almost perfect copy. It then begins the long return journey to Earth.
| Directing | George Spenton-Foster | Director |
| Writing | Alan Nourse | Story |
| Writing | Philip Broadley | Adaptation |
| Production | Irene Shubik | Producer |
| Production | George Spenton-Foster | Associate Producer |