Doctor Who newsletter
The Doctor delivered to your inbox
Be the first to know about the latest Doctor Who products and updates.
"UNIT, Sir, was set up to deal with new and unusual menaces to mankind. And in my view, this machine of yours is just that"
Professor Keller has created a machine that can pacify even the most dangerous of criminals. But when the Doctor and Jo arrive at Stangmoor Prison for a demonstration, things start to go horribly wrong – especially when they discover that the Doctor’s old enemy the Master is responsible for the machine. What could he possibly want from the criminals? And what connects him with an impending World Peace Conference?
The Doctor: Jon Pertwee
Jo Grant: Katy Manning
Brigadier Lethbridge-Stewart: Nicholas Courtney
The Master: Roger Delgado
Captain Mike Yates: Richard Franklin
Sergeant Benton: John Levene
Captain Chin Lee: Pik-Sen Lim
Dr. Summers: Michael Sheard
Mailer: William Marlowe
Barnham: Neil McCarthy
Producer: Barry Letts
Director: Timothy Combe
Scriptwriters: Don Houghton