Logopolis

Logopolis is the seventh and final serial of the 18th season of the British science fiction television series Doctor Who, which was first broadcast in four weekly parts on BBC1 from 28 February to 21 March 1981. The serial is set on the planets Earth and Logopolis. In the serial, the Doctor, a time traveller from the planet Gallifrey, forms a temporary truce with his arch-enemy the Master (Anthony Ainley) to stop the unravelling of the universe which the Master had started by accident. Logopolis is Tom Baker's last story as the Fourth Doctor, and marks the first appearances of Peter Davison as the Fifth Doctor and Janet Fielding as new companion Tegan Jovanka. The serial received positive reviews with many calling it a worthy farewell to Tom Baker as the Fourth Doctor. Baker's performance received much praise from critics.