Events unfold in France eighteen years after the end of the First World War. Gaston, a man who fought against Germany and lost his memory at the end of the war, together with Metro Yuspard, his attorney representing him, and the Duchess Dupont-Dupont, the patroness lady of the mental institution where Gaston spent the last eighteen years, come to a rich provincial house belonging to Messrs. Reno - the alleged family of Gaston. Several families whose members went missing during the war claim kinship with Gaston. Many of them were probably attracted by his disability pension, which he had not had the right to dispose of all these years and which now amounts to two hundred and fifty thousand francs.

Gaston should have had a meeting with the other four families even earlier, but the duchess decided to give priority to the Renault family, taking into account her social position and well-being. Gaston had already seen more than one family who came to a shelter to meet with him, but none of them evoked memories in him.

The head waiter warns guests about the appearance of Renault, and they temporarily send Gaston out for a walk in the garden. The living room includes the alleged mother of Gaston, or rather, the mother of Jacques - that was the name of her missing son; his brother, Georges, and the wife of Georges, Valentine. After mutual greetings, Mrs. Renault expresses indignation at the way in which confrontations with patients were arranged at the former managing director of the shelter. Then they saw Gaston in just a few seconds. Mrs. Renault and her daughter-in-law stopped after that meeting at the hotel, hoping to look at Gaston even once more. Valentina even got a seamstress in the shelter to be closer to him.

Gaston enters. As before, he does not recognize anyone. At the same time, a servant crowds behind the door and animatedly discusses the newcomer. It seems to almost all of them that they recognize in Gaston their former master, Jacques, the youngest son of Mrs. Renault, but none of them express the slightest enthusiasm about this, because everyone except the maid Juliette did not see anything good from him in the past and were glad to hear of his death.

Mrs. Reno and Georges take Gaston to Jacques's room, furnished with ridiculous furniture made according to the drawings of Jacques himself. Gaston examines some unusual building made of wood, as if curved by a storm. Mrs. Renault tells Gaston that as a child, he hated to play music and furiously crushed violins with heels. A music stand for notes is the only thing left from that time. He looks at his photograph at the age of twelve. He always believed that he was a blonde, a shy child, but Mrs. Renault assures that he was a dark brown-haired man, drove football all day and destroyed everything in his path. Soon, Gaston becomes aware of the other circumstances of Jacques’s life,

He learns that as a child he loved to shoot from a slingshot and destroyed all the valuable birds in his mother’s aviary, and once he broke a dog’s paw with a stone. Another time, he caught a mouse, tied a thread to her tail and dragged it along with him all day. Some time later, he killed many unfortunate animals: squirrels, weasels, ferrets, and ordered the most beautiful stuffed animals. Gaston is at a loss. He wonders if he had a friend in his childhood, with whom he never parted, exchanged thoughts. It turns out that he really had a friend, but during the fight with Jacques, he fell down the stairs, broke his spine and was forever paralyzed. After this incident, friends stopped talking. Gaston asks to show him the place of the fight. He feels that his alleged relatives are clearly not saying anything. Gaston finds out that Juliet was a servant at the fight. He asks her to come and asks the girl in detail about the circumstances of the accident. Juliet excitedly tells Gaston that before the call of Jacques to the war, she was his mistress. His friend also tried to look after her; when Jacques found him kissing Juliette, he had a fight with him, but when he fell, Jacques dragged him by the legs to the edge of the stairs and pushed him down.

Georges enters Jacques room and Juliette has to retire. Georges reassures Gaston, assuring that it was only an accident, childishness. He himself, not knowing much and not believing the rumors, believes that this was a fight, the cause of which was the rivalry of sports clubs. From George Gaston learns that Jacques is guilty of other crimes. At one time, he charmed a longtime friend of the family, an elderly lady, and lured her five hundred thousand francs, allegedly as an intermediary of some large company. He signed a fake bill, and when everything opened, Jacques had only a few thousand francs. The rest he lowered in some dens. The family had to pay a huge amount. After all these stories, Gaston is truly delighted with the joy with which Reno is preparing to once again take his son and brother into the bosom of his family,

However, it turns out that the list of his “exploits” is not yet complete. In addition to everything else, he also seduced George's wife, Valentina. They cannot continue the conversation because of the appearance of Mrs. Renault. She announces the arrival of numerous relatives who want to greet the returning Jacques. Gaston is not enthusiastic about the procedure ahead of him.

He asks Mrs. Renault if there were any joys in Jacques's life that were not related to school, even in that short period of time when he had already said goodbye to his textbooks, but had not yet picked up a rifle. It turns out that at that time, almost a year, the mother did not talk to him, because before that he insulted her and did not apologize. Jacques even went to the front, not saying goodbye to his mother, for not one of them wanted to take the first step towards the other. Gaston, in a fit of indignation at the fact that his mother had let her son go to the war without even saying goodbye, repeats the words of Jacques, said to him at seventeen, when his mother did not allow him to marry a seamstress. He says that he hates her and does not want to be called Jacques.

After the departure of mother Jacques and his brother, Valentine appears in the room. She reminds him of their former love and insistently demands restoration of the former relations. Gaston never wants to become a traitor to his brother twice, he is not at all sure that he is Jacques and that he will remain in this house. Then Valentina points him to irrefutable evidence: Jacques has a small scar under his shoulder blade that the doctors did not notice. Valentina herself left this mark on Jacques with a hat pin when she decided that he was cheating on her. When she leaves, Gaston discovers this scar and weeps bitterly.

The next morning, the other four families, claiming kinship with Gaston, are at Renault's house. Among them is a boy who came from England with his lawyer, Maitre Pickwick. A boy, wandering around the house, accidentally enters Gaston's room. He tells him what the alleged uncle Gaston has to do, that all his relatives and friends sank along with the Neptune ship when he was still a baby. After talking with the boy’s lawyer, Gaston informs the Duchess that he is the boy’s wanted nephew, and will leave Reno’s home forever, because he does not want to start a new life with the baggage of old sins and is constantly surrounded by countless relatives who will look at him every minute about remind them.