Episode Six
Series Episode Number: 288World Premiere: Sat 6 Mar 1971 - 5:15pm BST [BBC One] (United Kingdom)
First Broadcast: Fri 14 Nov 1975 - 6:30pm CST [WTTW 11 Chicago]
Running Time: 24 minutes 48 seconds
7.30 Million (UK)
Chart Position: 65 () (UK)
Recorded on Sat 19 Dec 1970 in Television Centre 3
Archive State: 16mm t/r
The Keller Machine breaks free of the Doctor's restraining device and the Doctor has no choice but to turn the parasite against the Master.