175 minutes
5/2/1970
Astronauts rescued from a mission to mars are kidnapped when they arrive back on earth. They seem to have been irradiated, and can now kill people merely by touching them. But the Doctor discovers the astronauts have been replaced with Alien ambassadors who are being forced to behave in a hostile manner. With The Doctor traveling to the alien mother ship, and Liz kidnapped, The Brigadier is left wondering who to trust.
Jon Pertwee
as The Doctor
Caroline John
as Liz Shaw
Nicholas Courtney
as Brigadier Lethbridge-Stewart
Ronald Allen
as Ralph Cornish
John Abineri
as Carrington
Robert Cawdron
as Taltalian
Michael Wisher
as John Wakefield
Cheryl Molineaux
as Miss Rutherford
Ray Armstrong
as Grey
Robert Robertson
as Collinson
Ric Felgate
as Van Lyden / Alien Ambassador
Dallas Cavell
as Quinlan
Bernard Martin
as Control Room Assistant
John Moreno
as Dobson
James Haswell
as Corporal Champion
Derek Ware
as UNIT Sergeant
William Dysart
as Reegan
Cyril Shaps
as Lennox
Gordon Sterne
as Heldorf
Steve Peters
as Alien Ambassador / Lefee
Neville Simons
as Alien Ambassador / Michaels
Max Faulkner
as UNIT Soldier
John Lord
as Masters
Tony Harwood
as Flynn
John Levene
as Sergeant Benton
James Clayton
as Private Parker
Joanna Ross
as Control Room Assistant
Carl Conway
as Control Room Assistant
Roy Scammell
as Technician
Peter Noel Cook
as Alien Space Captain
Peter Halliday
as Aliens' Voices
Geoffrey Beevers
as Private Johnson