With the newly-regenerated Doctor behaving erratically, Brigadier Lethbridge-Stewart and UNIT have to contend with the theft of the plans for the new disintegrator gun by what seems to be a mechanical monster. However, the theft is only the beginning of a plot to hold the world to nuclear ransom.
Commentary by Tom Baker, Elisabeth Sladen, Terrance Dicks and producer Barry Letts
Are Friends Electric? A full-length documentary covering Tom Baker's debut
The Tunnel Effect: A fourteen-minute featurette in which Bernard Lodge talks about creating the opening "never-ending tunnel" sequence for Tom Baker's era
Episode of Blue Peter broadcast from the Robot set
Photo Gallery
Production Notes
Radio Times Listings in pdf format