On the planet Vortis, the Doctor and his companions aid the butterfly-like Menoptra in their battle against the parasitic Animus and its mind-controlled minions, the ant-like Zarbi.
| Writing | Bill Strutton | Writer |
| Production | Verity Lambert | Producer |
| Writing | Dennis Spooner | Script Editor |
| Directing | Richard Martin | Director |
| Camera | Peter Hamilton | Camera Operator |
| Editing | Gitta Zadek | Editor |
| Costume & Make-Up | Daphne Dare | Costume Design |
| Costume & Make-Up | Sonia Markham | Makeup Artist |
| Lighting | Ralph Walton | Lighting Director |
| Sound | Ray Angel | Sound |
| Crew | Roslyn de Winter | Choreographer |
