A lost expedition. And the prisoner? DOCTOR: Hmm? SARAH: Where? The last planet of the known universe. We picked up a distress call and landed immediately.
Plan: A: a distress call; Q: What do the Doctor and Sarah answer? A: Zeta Minor; Q: What is the name of the planet where the Doctor and Sarah find themselves? A: a Morestran expedition; Q: What has gone missing on Zeta Minor? Summary: The Doctor and Sarah answer a distress call and find themselves on Zeta Minor, the last planet of the known universe, where a Morestran expedition has gone missing.