Nicholas Courtney (Brigadier Lethbridge-Stewart), Ronald Allen (Ralph Cornish), Robert Cawdron (Taltalian) [1-2, 4], John Abineri (Carrington / General Carrington)&dagger,, Ric Felgate (Van Lyden) [1-3, 6], Michael Wisher (John Wakefield) [1-2, 7], Cheryl Molineaux (Miss Rutherford) [1-2], Ray Armstrong (Grey) [1-2], Robert Robertson (Collinson) [1-2], Dallas Cavell (Quinlan) [2-5], Bernard Martin , Joanna Ross [5-7], Carl Conway [5-6] (Control Room Assistant), Juan Moreno (Dobson) , James Haswell (Corporal Champion) , Derek Ware (Unit Sergeant) , William Dysart (Reegan) [3-7], Cyril Shaps (Lennox) [3-5], Gordon Sterne (Heldorf) , Steve Peters [3-5, 7], Neville Simons [3-5, 7], Ric Felgate [4-5, 7] (Astronauts), Max Faulkner (Unit Soldier) , John Lord (Masters) , Tony Harwood (Flynn) , John Levene (Sergeant Benton) [5, 7], James Clayton (Private Parker) , Roy Scammell (Technician) , Peter Noel Cook (Alien Space Captain) [6-7], Peter Halliday (Aliens’ Voices) [6-7], Steve Peters (Lefee) , Neville Simons (Michaels) , Geoffrey Beevers (Private Johnson) .
|Written by||David Whitaker|
|Directed by||Michael Ferguson|
|Produced by||Barry Letts|
When all communication is lost from Mars Probe 7 shortly after it leaves Mars and begins its trip back to Earth, a second craft is launched to investigate. As Recovery 7 docks in space, it too loses all communication…
The Doctor and UNIT are given the task of investigating the mystery, as Recovery 7 returns to Earth. It appears that no one can be trusted, as the space capsule is hijacked from its UNIT convoy with military precise. What has happened to the missing astronauts? Could this be a secret invasion from Mars, or is the enemy much closer to home?
As The Doctor plans a daring space mission of his own, his assistant Liz Shaw goes missing. Who is working against UNIT in order to bring mankind into conflict with an alien race…?