The Doctor is sentenced to life imprisonment at a lunar penal colony while Jo encounters an old enemy.
| Name | Type | Role | |
|---|---|---|---|
| Malcolm Hulke | Writer | ||
| Caroline Hunt | Guest Star | ||
| Madhav Sharma | Guest Star | ||
| Luan Peters | Guest Star | ||
| Harold Goldblatt | Guest Star | ||
| Karol Hagar | Guest Star | ||
| Laurence Harrington | Guest Star | ||
| Dennis Bowen | Guest Star | ||
| Paul Bernard | Director |