Without the Professor, the Doctor and Romana are forced to think on their feet. But what large invisible object lurks nearby?
| Name | Type | Role | |
|---|---|---|---|
| Douglas Adams | Writer | ||
| David Brierley | Guest Star | ||
| David Daker | Guest Star | ||
| Jennifer Lonsdale | Guest Star | ||
| Stephen Jenn | Guest Star | ||
| Lewis Fiander | Guest Star | ||
| Richard Barnes | Guest Star | ||
| Geoffrey Bateman | Guest Star | ||
| Pennant Roberts | Director |