Episode 1
Series Episode Number: 272World Premiere: Sat 9 May 1970 - 5:15pm BST [BBC One] (United Kingdom)
First Broadcast: Wed 29 Oct 1975 - 6:30pm CST [WTTW 11 Chicago]
Running Time: 23 minutes 21 seconds
5.70 Million (UK)
Appreciation Index: 61 (UK)Chart Position: 72 () (UK)
Recorded on Fri 24 Apr 1970 in TC3 / TC6
Archive State: RSC conver
UNIT are at a project run by Professor Stahlman who plans to penetrate Earth's crust. But the drilling has already released something deadly from beneath the planet's surface.
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