In the distant future, the Doctor, Sarah and Harry find a space station preserving the future of mankind. But the insect Wirrn have got there first...
| Writing | Robert Holmes | Writer |
| Directing | Rodney Bennett | Director |
| Production | Philip Hinchcliffe | Producer |
| Costume & Make-Up | Barbara Kidd | Costume Design |
| Art | Roger Murray-Leach | Production Design |
| Sound | Dudley Simpson | Original Music Composer |
| Costume & Make-Up | Sylvia James | Makeup Artist |
| Production | Marion McDougall | Production Assistant |
| Writing | Robert Holmes | Script Editor |
| Crew | Dick Mills | Special Sound Effects |
| Lighting | Nigel Wright | Lighting Director |
| Sound | John Lloyd | Sound |
| Visual Effects | John Friedlander | Visual Effects |
| Visual Effects | Tony Oxley | Visual Effects |
