Last updated 09 January 2020


Part Four

Series Episode Number: 443

World Premiere: Sat 22 Jan 1977 - 6:26pm GMT [BBC One] (United Kingdom)
First Broadcast: Mon 26 May 1980 - 5:30pm CDT [WTTW 11 Chicago]
Running Time: 24 minutes 46 seconds

11.70 Million (UK)

Appreciation Index: 60 (UK)

Chart Position: 19 () (UK)

Recorded on Tue 26 Oct 1976 in TC3
BBC Genome Project: see entry



Determined to rectify his earlier mistake, the Doctor tries to repair Xoanon. But the insane computer refuses to accept his help and prepares to destroy the entire planet.