Featuring an all-star international cast including Peter Ustinov, Curt Jurgens, Sam Jaffe, Martita Hunt and Vera Clouzot, the film is filled with twists and turns. A dilapidated psychiatric hospital has subtly been taken over by a group of international spies. But when one of the patients, who has apparently invented a new weapon (thereby attracting the attentions of both Russia and America), is exposed as a fake, the entire espionage community is thrown into chaos and no-one knows who to trust anymore.