Two men let themselves be trapped in a vault for three days and three nights. One of them is there to replace some missing stocks and the other to steal the 200 million francs held in the safe. When they become aware of their opposing reasons for being in the room, a dispute develops. As soon as they open the safe, they realize that it was a set-up. The safe is empty and a guard has been murdered. Both manage to escape. United by the strange nature of their situation, they become friends and promise not to betray each other. One will be caught by the police and the other will try to prove his innocence.