Last updated 24 March 2024


Episode 1

Series Episode Number: 265

World Premiere: Sat 21 Mar 1970 - 5:16pm BST [BBC One] (United Kingdom)
First Broadcast: Mon 13 Oct 1975 - 6:30pm CDT [WTTW 11 Chicago]
Running Time: 24 minutes 33 seconds

7.10 Million (UK)

Appreciation Index: 60 (UK)

Chart Position: 60 () (UK)

Recorded on Fri 13 Feb 1970 in Television Centre 3
Archive State: PAL 2 VT



Contact has been lost with Mars Probe 7. When contact is also lost with the recovery ship, UNIT is called in and the Doctor learns that someone is sending messages to the vessel.


Characters hide uncredited
Doctor WhoJon Pertwee
Liz ShawCaroline John
Brigadier Lethbridge-StewartNicholas Courtney
Ralph CornishRonald Allen
TaltalianRobert Cawdron
Carrington John Abineri
Van LydenRic Felgate
John WakefieldMichael Wisher
Miss RutherfordCheryl Molineaux
GreyRay Armstrong
CollinsonRobert Robertson
Collinson's ManGarth Wilkins (uncredited)
Collinson's ManLeslie Shannon (uncredited)
Collinson's ManRay Mimins (uncredited)
Collinson's ManVernon Preston (uncredited)
Control Room AssistantCaroline Mylon (uncredited)
Control Room AssistantClive Rogers (uncredited)
Control Room AssistantLindsey Scott (uncredited)
Control Room AssistantRod Peers (uncredited)
Control Room AssistantRoger Minnis (uncredited)
Control Room AssistantRoy Brent (uncredited)
Control Room AssistantWilma Oswald (uncredited)
Stunt ManAlan Chuntz (uncredited)
Stunt ManDerek Ware (uncredited)
Stunt ManMax Diamond (uncredited)
Stunt PolicemanLes Clarke (uncredited)
Stunt ManTerry Walsh (uncredited)
Stunt ManBilly Horrigan (uncredited)
UNIT DriverBG Herth (uncredited)
UNIT DriverBruce Cox (uncredited)
UNIT DriverRichard Pickford (uncredited)
UNIT SoldierCrawford Lyall (uncredited)
UNIT SoldierDouglas Roe (uncredited)
UNIT SoldierEric Kent (uncredited)
UNIT SoldierJeff Brightly (uncredited)
UNIT SoldierKeith Simons (uncredited)
UNIT SoldierSteve Smart (uncredited)
UNIT SoldierStuart Myers (uncredited)
UNIT SoldierTom Laird (uncredited)