Episode 1
Series Episode Number: 258World Premiere: Sat 31 Jan 1970 - 5:15pm BST [BBC One] (United Kingdom)
First Broadcast: Mon 2 Feb 1976 - 10:00pm CST [WTTW 11 Chicago]
Running Time: 24 minutes 15 seconds
8.80 Million (UK)
Appreciation Index: 58 (UK)Chart Position: 41 () (UK)
Recorded on Mon 08 Dec 1969 in Television Centre 3
Archive State: PAL Restor
UNIT are summoned to Wenley Moor research station which is experiencing mysterious power losses. In the nearby caves, one of the staff has been killed and another sent insane.
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