Plot
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.
Writer | Don Houghton |
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Director | Timothy Combe |
Actor | Jon Pertwee, Katy Manning, Nicholas Courtney |
Country | United Kingdom |
Production | BBC |