Episode SixSeries Episode Number: 179
World Premiere: Sat 4 Nov 1967 - 5:25pm GMT [BBC One] (United Kingdom)
Running Time: 23 minutes 51 seconds
7.40 Million (UK)Appreciation Index: 52 (UK)
Chart Position: 56 () (UK)
Recorded on Sat 14 Oct 1967 in Lime Grove D
Archive State: Missing
As the Great Intelligence manifests itself on Earth, the Doctor makes a last, desperate attempt to repel the evil entity by pitting his mind against it in a mental battle.