Doctor Who: The Mind of Evil (06/03/1971)

Production : BBC

Synopsis

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.

Jon Pertwee

Katy Manning

Nicholas Courtney

Richard Franklin