

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.
Director
Timothy Combe
Writers
Don Houghton
Release Date
March 6, 1971
Runtime
2h 30m
Status
Released
Original Language
en
Vote Count
11
