Plot
Professor Emil 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.
Trailer
Cast
Jon Pertwee
The Doctor
Katy Manning
Jo Grant
Nicholas Courtney
Brigadier Lethbridge-Stewart
Richard Franklin
Captain Mike Yates
John Levene
Sergeant Benton
Roger Delgado
The Master
Pik-Sen Lim
Captain Chin Lee
Raymond Westwell
Prison Governor
Michael Sheard
Dr. Roland Summers
Simon Lack
Professor Kettering
Fernanda Marlowe
Corporal Bell
Neil McCarthy
George Patrick Barnham
Clive Scott
Arthur Linwood
Roy Purcell
Chief Prison Officer Powers
Eric Mason
Senior Prison Officer Green
Bill Matthews
Prison Officer
Barry Wade
Prison Officer
Dave Carter
Prison Officer
Martin Gordon
Prison Officer
William Marlowe
Mailer
Hayden Jones
Vosper
Kristopher Kum
Fu Peng
Tommy Duggan
Senator Alcott
David Calderisi
Charlie
Patrick Godfrey
Major Cosworth
Johnny Barrs
Fuller
Matthew Walters
Main Gates Prisoner
Timothy Combe
Prisoner (uncredited)
