Parts: 6
Writer: Douglas Adams
Airdates: n/a
Production Code: 5M

Doctor: fourth
Companions: the second Romana, K-9 mark two

Megalomaniac of the Week: Skagra

Story: The Doctor and Romana visit Cambridge in October 1979 to find Professor Chronotis, a retired Time Lord who has been living in the same set of rooms at St Cedd's for three hundred years. Chronotis has in his possession several books from Gallifrey, one of which - The Worshipful and Ancient Law of Gallifrey - could be dangerous in the wrong hands. Chronotis wishes to have the Doctor return the book to Gallifrey - but unbeknownst to him, one of his students has just borrowed it.

The Doctor and Romana are not the only aliens who have come to Cambridge in search of Chronotis. Also present is Skagra, who wants The Worshipful and Ancient Law of Gallifrey...at any cost. Armed with a mind-stealing sphere, he extracts part of Chronotis' mind to discover the book's whereabouts - leaving the professor unable to function, and slowly dying.

From the book, Skagra desires to learn the location of Shada, the Time Lords' ancient time prison about which even they have forgotten. Imprisoned there is the infamous criminal Salyavin, the key to Skagra's plan for total domination. Unless the Doctor, Romana and K-9 can stop Skagra from absorbing Salyavin's mind into his brain-draining sphere, he will control the minds of everyone in the universe...

Notes: Due to ill-timed strikes at the BBC, Shada was indefinitely delayed and eventually cancelled, and therefore has never been aired. In 1992, a video containing all filmed sequences was released with linking narration by Tom Baker.