'Beware the sphere. Beware Skagra. Beware Shada. The secret is in the...' What can the Professor's cryptic last message mean?
| Name | Type | Role | |
|---|---|---|---|
| Douglas Adams | Writer | ||
| David Strong | Guest Star | ||
| John Hallett | Guest Star | ||
| Shirley Dixon | Guest Star | ||
| Daniel Hill | Guest Star | ||
| Christopher Neame | Guest Star | ||
| Derek Suthern | Guest Star | ||
| Victoria Burgoyne | Guest Star | ||
| David Brierley | Guest Star | ||
| James Coombes | Guest Star | ||
| Lionel Sansby | Guest Star | ||
| James Muir | Guest Star | ||
| Reg Woods | Guest Star | ||
| Harry Fielder | Guest Star | ||
| Gerald Campion | Guest Star | ||
| Pennant Roberts | Director |