Doctor Who: The Mind of Evil

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.

Starring: Jon Pertwee, Katy Manning, Nicholas Courtney, Richard Franklin, John Levene