British spymaster Tweed thinks one of his four European section chiefs is a double agent and possibly a mass murderer. Tweed goes to Germany, where one of his top agents was killed, obviously betrayed by the traitor. The Russians and East Germans, hoping to kill Tweed, lead him to Lubeck, home of mysterious philanthropist Dr. Berlin. Deliberately using himself as bait to flush the two-faced "Janus,” Tweed is saved from assassination in Lubeck only with the help of Bob Newman. Eventually Tweed uncovers a Russian plot fostered by a tough-talking Gorbachev to flood England with heroin, which the Soviets assume will destroy the country.