The Doctor and Romana trace the second segment of the Key to Time to the cold, uninhabited planet Calufrax. Only, when they arrive, they find that the TARDIS has actually materialized on the planet Zanak. Zanak, a populated world teeming with advanced technology and an overabundance of precious gems, appears to be lorded over by the tyrannical and partially mechanical Captain. But Zanak also holds a dark secret and only by teaming up with the Mentiads, a mysterious group with psychic powers, will the Doctor and his companions be able to uncover the mystery of Zanak and find the next piece of the Key to Time.
The Pirate Planet is probably most famous for being the first contribution to
Doctor Who by Douglas Adams. Adams would go on to write two more stories for
Doctor Who as well as being the script supervisor for the show's following season. There is some overlap, both in concepts and characters, between Adams' work on
Doctor Who and
The Hitchhiker's Guide to the Galaxy, which is hardly surprising given that he was working on both around the same time.
Rating: Don't panic%