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.
Timothy Combe
Director
Don Houghton
Writer

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
Doctor Who: Deep Breath77%
Omni Loop59%
Timescape64%
The Last Mimzy63%
Doctor Who: Last Christmas77%
Monster High 268%
Doctor Who: The Day of the Doctor81%
Vesper63%
Stargate: Continuum71%
Solo: A Star Wars Story65%
The Time Machine63%
Star Wars: The Rise of Skywalker62%
Star Trek: The Motion Picture64%
F.R.E.D.I.59%
Stowaway60%
Guardians of the Galaxy79%
The Mandela Effect63%
Halo: Nightfall67%
Doctor Who62%
Return from Witch Mountain58%