The Doctor, Ace, K9 and Cedric are taking part in a game show to see who can win The Ultimate Challenge — the biggest game show in the universe. The contestants are forced to answer fairly basic questions about space, with severe punishments if they get it wrong.
| Actor | Role |
|---|---|
 Sylvester McCoyThe Doctor | The Doctor |
 Sophie AldredAce | Ace |
| SStephen JohnsonCedric | Cedric |
 John LeesonK9 (voice) | K9 (voice) |