The HQ is destroyed by the web and everyone is captured by Yetis. The traitor is revealed and all seems lost as the Doctor submits himself to the Great Intelligence's mind drain.
| Name | Type | Role | |
|---|---|---|---|
| Mervyn Haisman, Henry Lincoln | Writer | ||
| Roger Jacobs | Guest Star | ||
| Jon Rollason | Guest Star | ||
| Douglas Camfield | Director |