Last updated 24 March 2024


Episode 1

Series Episode Number: 258

World 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.


Characters hide uncredited
Doctor WhoJon Pertwee
Liz ShawCaroline John
Brigadier Lethbridge-StewartNicholas Courtney
Dr. QuinnFulton Mackay
Major BakerNorman Jones
Dr. LawrencePeter Miles
Miss DawsonThomasine Heiner
Dr. MeredithIan Cunningham
RobertsRoy Brannigan
SpencerJohn Newman
DavisBill Matthews
UNIT SoldierJohn Spradbury (uncredited)
ReceptionistSheila Knight (uncredited)
Security GuardBrian John (uncredited)
Security GuardPatrick Milner (uncredited)
TechnicianAlan Vicars (uncredited)
TechnicianAlex Hood (uncredited)
TechnicianBarry Kennington (uncredited)
TechnicianCara Stevens (uncredited)
TechnicianCy Town (uncredited)
TechnicianDavid Billa (uncredited)
TechnicianJoan Harsant (uncredited)
TechnicianKeith Ashley (uncredited)
TechnicianKeith Goodman (uncredited)
TechnicianMargaret Pilbeau (uncredited)
TechnicianMary Denton (uncredited)
TechnicianMichael Earl (uncredited)
TechnicianMichael Lomax (uncredited)
TechnicianNorton Clark (uncredited)
TechnicianRichard Lawrence (uncredited)
TechnicianRonald Gough (uncredited)