Director :
Stars :
Jon PertweeKaty ManningNicholas CourtneyRichard FranklinJohn LeveneRoger DelgadoPik-Sen LimRaymond WestwellMichael SheardSimon Lack
Genre :
Release :
1971-03-06
Rating :
7
Story :
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.