Last updated 24 March 2024


Episode 7

Series Episode Number: 278

World Premiere: Sat 20 Jun 1970 - 5:15pm BST [BBC One] (United Kingdom)
First Broadcast: Thu 6 Nov 1975 - 6:30pm CST [WTTW 11 Chicago]
Running Time: 24 minutes 33 seconds

5.50 Million (UK)

Appreciation Index: 60 (UK)

Chart Position: 79 () (UK)

Recorded on Fri 29 May 1970 in TC3 / TC6
Archive State: RSC conver



The Doctor has escaped the doomed, parallel Earth and has returned to his own world where he attempts to put a halt to the drilling project.


Characters hide uncredited
Doctor WhoJon Pertwee
Liz ShawCaroline John
Brigadier Lethbridge-StewartNicholas Courtney
Professor StahlmanOlaf Pooley
Sir Keith GoldChristopher Benjamin
Greg SuttonDerek Newark
Petra WilliamsSheila Dunn
Sergeant BentonJohn Levene
BromleyIan Fairbairn
Loudspeaker VoiceIan Fairbairn (uncredited)
Soldier (UNIT)Alan Chuntz (uncredited)
Soldier (UNIT)Ian Elliott (uncredited)
Technician (inferno Project)Patricia Matthews (uncredited)
Technician (inferno Project)Sheila Knight (uncredited)
Technician (inferno Project)Corrine Skinner (uncredited)
Technician (inferno Project)Joan Harsant (uncredited)
Technician (inferno Project)Judith Pollard (uncredited)
Technician (inferno Project)Sue Paterson (uncredited)
Technician (inferno Project)Marcelle Elliott (uncredited)
Technician (inferno Project)Colin James (uncredited)
Technician (inferno Project)Alan Clements (uncredited)
Technician (inferno Project)Alistair Baine (uncredited)
Technician (inferno Project)Robert Birmingham (uncredited)
Technician (inferno Project)Derek Hunt (uncredited)
Technician (inferno Project)Barry Ashton (uncredited)
Technician (inferno Project)Keith Norrish (uncredited)
Technician (inferno Project)Keith Ashley (uncredited)
Technician (inferno Project)Norton Clarke (uncredited)
Technician (inferno Project)Steve Tierney (uncredited)
Technician (inferno Project)Richard Lawrence (uncredited)
Technician (inferno Project)Cy Town (uncredited)
Stunt ManTerry Walsh (uncredited)
Stunt ManDerek Martin (uncredited)