Standard Definition

Originally aired on

18 January 1975

Written by

Terrance Dicks

Directed by

Christopher Barry

Cast List

Tom Baker- The Doctor
Elisabeth Sladen- Sarah Jane Smith
Ian Marter- Harry Sullivan
Nicholas Courtney- Brigadier Lethbridge-Stewart
John Levene- Sergeant Benton
Patricia Maynard- Miss Winters
Michael Kilgarriff- Robot
Edward Burnham- Professor Kettlewell
Alec- Linstead Jellicoe
Timothy Craven- Short

Synopsis

With the Doctor behaving rather oddly after his regeneration, the Brigadier finds a scientific research station under attack after a robot steals the plans for a new disintegrator gun. Could the members of the mysterious Think Tank be responsible for the giant invader? How sinister are the intentions of the shadowy Scientific Reform Society? More importantly, can the Doctor recover in time to save the Earth from Atomic War?