By late 1944, it is obvious that the Germans will lose the war. American Colonel Devlin (Gary Merrill) leads a Military Intelligence Corps (United States Army) unit that recruits German Prisoner of war to spy on their former comrades. "Tiger" (Hans Christian Blech), a cynical, older thief and ex-circus worker, is willing to work for the winning side. On the other hand, "Happy" (Oskar Werner) is a young idealist who volunteers to spy after his friend is killed by fanatical fellow prisoners for voicing doubts about the war's outcome. Monique (Dominique Blanchar) trains Happy and the others in espionage techniques; she takes a liking to the young man despite her hatred for Germans.