A man is found in 1918 on a railway siding, having come off a train loaded with returning prisoners of war. He has amnesia, and nothing is known about him. He is given the name Gaston. Gaston spends more than a dozen years in a mental institution, largely ignored. Despite his surroundings, he is kind, sane and down-to-earth. This peace is shattered when a new psychiatrist comes along and decides to find out who Gaston really is. Another reason to determine his identity lies in the fact that several families have come forward to claim Gaston as their own, mainly because he receives a large disability allowance. He is brought to one family who believes he is actually Jacques, the son they thought lost in the war. Their remembrances of Jacques, however, are disturbing to gentle Gaston. They tell of an arrogant, aristocratic bully who crippled his best friend, killed animals and slept with his brother's wife. He is horrified by this image of himself and denies that he was this monster. The sister-in-law convinces him that he is Jacques by referring to a scar on the back of his shoulder. Even with this evidence, Gaston/Jacques escapes this identity. He deals with another family, and even though he knows he is Jacques, he pretends to be someone else. He thus releases the fetters of his past and emerges from his existential crisis.