Tom Baker’s final story as The Doctor, and debut of Janet Fieldings appearance as Tegan The Doctor takes Adric and a young air hostess named Tegan Jovanka, who has come aboard the TARDIS by accident, to the planet Logopolis, home of a race of mathematicians whose help he hopes to enlist in reconfiguring the outer shell of the TARDIS. The mysterious, wraith-like Watcher brings Nyssa from Traken to join them and warns of impending danger – something that is borne out as The Master arrives and kills a number of the Logopolitans
- Logopolis is the seventh and final serial of the 18th season in the British science fiction television series Doctor Who, which was first broadcast in four weekly parts from 28 February to 21 March 1981.
- It was Tom Baker’s last story as the Fourth Doctor and marks the first appearance of Peter Davison as the Fifth Doctor.
- This serial also marks the first appearance of Janet Fielding as new companion Tegan Jovanka, whilst Nyssa, played by Sarah Sutton and seen in previous serial The Keeper Of Traken, returns and also joins The Doctor as a companion.