The Doctor's TARDIS is stolen, and tracking it down reveals the existence of an alien named Kalid controlling events in the past. While the Doctor challenges Kalid's motives for being there, Tegan and Nyssa discover the source of Kalid's power - an even greater threat for the Doctor.
| Name | Type | Role | |
|---|---|---|---|
| Peter Grimwade | Writer | ||
| Michael Cashman (First Officer Bilton) | Guest Star | ||
| Judith Byfield (Angela Clifford) | Guest Star | ||
| Keith Drinkel (Flight Engineeer Scobie) | Guest Star | ||
| Hugh Hayes (Anithon) | Guest Star | ||
| Peter Dahlsen (Horton) | Guest Star | ||
| Richard Easton (Captain Stapley) | Guest Star | ||
| Peter Cellier (Andrews) | Guest Star | ||
| John Flint | Guest Star | ||
| Ron Jones | Director |