Overview

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.

Details

Cast

Jon Pertwee

Katy Manning

Nicholas Courtney

Richard Franklin

John Levene

Roger Delgado

Pik-Sen Lim

Raymond Westwell

Michael Sheard

Simon Lack