Science FictionDramaAdventure

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.

Credits

Jon PertweeThe Doctor

Katy ManningJo Grant

Nicholas CourtneyBrigadier Lethbridge-Stewart

Richard FranklinCaptain Mike Yates

John LeveneSergeant Benton