The Hideout (1962)

Set during World War II in France, the story begins when a resistance fighter is given shelter in an asylum by a friend who manages the institution. Soon after, the manager is arrested by the Gestapo, which gets the resistance fighter involved. He finds the informer who set his friend up and kills him. But then no one will believe his story about the informer and he becomes desperate enough to start losing his own mental balance. A young doctor and the daughter of one of the inmates help him keep it together, but he knows he cannot continue like this for long.