Venue - Paris and the Swiss village of Saas-Fee. Time is deliberately not specified. At the center of the story are three families - Profitandier, Molyneux, and Azais-Vedel. The old music teacher Laleruz is closely connected with them, as well as two writers - Count Robert de Passavan and Edward. The latter keeps a diary where he enters his observations and analyzes them from the point of view of a future novel, which has already received the name "Counterfeiters". In addition, the voice of the author intrudes into the text, commenting on the actions of his heroes.

Seventeen-year-old Bernard Profitandier leaves home, learning about his illegal origin. He is convinced that he always hated the man whom he considered his father. However, the judicial investigator Profitandier loves Bernard much more than his own sons - Charles's lawyer and Kalu, a schoolboy. Both lack the unbridled strength of character that distinguishes Bernard.

Olivier Molyneux also admires the friend’s resolve. Tender Olivier needs spiritual support: he is deeply attached to Bernard and is looking forward to the return from England of his uncle Edward, the only person in the family who can speak heart to heart. On the eve of Olivier became an involuntary witness to a terrible scene: at night a woman sobbed under the door - apparently, it was the mistress of his older brother Vincent.

Vincent got in touch with Laura Duvier in a tuberculosis sanatorium, when both of them believed that they did not have long to live. Laura is pregnant, but does not want to return to her husband. Vincent cannot contain it, because he has put all his money into cards. Count de Passavan, who has his own secret reasons, wanted him to play. Robert gives Vincent an opportunity to recoup and gives him his own mistress - Lady Lilian Griffith. Vincent is smart, handsome, but completely devoid of secular gloss, and Lillian gladly takes up his education. In exchange, Robert asks for a small service: Vincent should bring him to his younger brother Olivier.

On the train, Edward looks in exasperation at the recently published Passavan book - as brilliant and fake as Robert himself. Edward re-reads the letter in which Laura begs for help, and then writes thoughts about the novel in the diary: in the era of cinema, action should be abandoned.

The long-awaited meeting with uncle does not bring joy to Olivier: both behave constrained and cannot express their overwhelming happiness. The lost luggage receipt is picked up by Bernard. In the suitcase is a diary with notes a year ago. Edward then caught the hand on the theft of the youngest of the Molyneux brothers - Georges. Nephews study at the guesthouse of Pastor Azais. - Grandfather Laura, Rachelle, Sarah and Arman Vedel. Laura endlessly returns to the past - to the days when he and Edward wrote their names on the windowsill. Rachelle actually abandoned her personal life and draws on herself the whole economy. Young Sarah is openly trying to seduce Olivier - not without reason the cynical Arman calls his sister a prostitute. Something is wrong with the pious Protestant family, which is why Laura should marry an honest, albeit not-so-distant, Duvier - because Edward himself is not able to make her happy. Old Azais praises Georges very much: dear kids organized something like a secret society, where only the worthy are accepted, - the yellow ribbon in the buttonhole is the distinction. Edward has no doubt that the cunning boy deftly led the pastor. It is equally painful to watch Laperouz. The former music teacher is deeply unhappy: he has almost no students left, his once beloved wife is annoying, his only son is dead. The old man broke off relations with him because of his affair with a Russian musician. They left for Poland, but never got married. Grandson Boris does not suspect the existence of a grandfather. This boy is the most expensive creature for Laleruz.

Comparing Olivier's story with Edward's diary, Bernard realizes that Laura was sobbing under the door of Vincent. The letter contains the address of the hotel, and Bernard immediately goes there. The circumstances favor the young adventurer: both Laura and Eduard like his impudent self-confidence. Bernard receives the post of secretary at Edward. Together with Laura, they go to Saas-Fee: according to Laperouse, Boris is spending his holidays here. Meanwhile, Olivier met Passavan, and he invited him to become the editor of the Argonauts magazine. In a letter from Switzerland, Bernard tells Olivier about his acquaintance with his uncle, confesses his love for Laura and explains the purpose of their visit: Edward for some reason needed a thirteen-year-old boy who is under the supervision of a Polish female doctor and is very friendly with her daughter Brona. Boris suffers from some kind of nervous disease. The author notes that Bernard did not foresee what a storm of low feelings would cause his letter in the soul of a friend. Olivier feels severe jealousy. At night he is visited by demons. In the morning he leaves for the Count de Passavan.

Eduard writes in the doctor’s observation diary: Sofronitskaya is sure that Boris is hiding some shameful secret. Edward unexpectedly tells his friends the idea of ​​the novel "Counterfeiters". Bernard advises starting the book with a fake coin, which he slipped in the shop. Sofronitskaya shows Boris’s "talisman": this is a piece of paper with the words "Gas. Telephone. One hundred thousand of rubles". It turns out that at nine years old a school friend introduced him to a bad habit - naive children called it "magic." It seems to Edward that the doctor unscrewed all the wheels of the boy’s mental mechanism. Boris cannot live without chimeras - perhaps staying at Azais Guesthouse will benefit from it. A letter comes from Olivier, where he tells in enthusiastic tones about a trip to Italy in the company of Robert. The author notes with concern that Edward makes a clear oversight - he knows how the atmosphere in the house of the Azais - Vedel is poisoned. Edward seems to be lying to himself, and the devil whispers advice to him. It is a pity that, at the whim of fate, Bernard took the place intended by Olivier. Edward loves his nephew, and Passavan will ruin this fragile young man. But Bernard, under the influence of love for Laura, is clearly changing for the better.

Returning to Paris, Edward introduces Boris to his grandfather. Molyneux Sr. tells Edward about his troubles: he started a small affair on the side, and his wife, apparently, found love letters. Olivier’s friendship with Bernard also worries him: the judicial investigator Profitandier is conducting a case of a brothel of corruption where schoolchildren are lured, and nothing good can be expected from Bernard, because he is illegitimate.

Edward arranges Bernard as a teacher in the boarding house of Azais. Old man Laperuz also moves there to be closer to Boris. The boy was immediately disliked by the most lively of the students, Leon Geridanizol, the nephew of Victor Struvil, who had once been expelled from the guesthouse, and now is selling counterfeit coins. Geri's company includes Georges Molyneux and several other schoolchildren - all of them were regulars in the same "brothel of debauchery" that the prosecutor Molyneux had told Edward about. After a police raid, the boys have to take out the yellow ribbons from their buttonholes, but Leon is ready to offer them a new interesting business. Polina Molyneux shares her suspicions with her brother: money began to disappear in the house, and recently the letters of her mistress to her husband disappeared - Polina herself found them a long time ago, and it did not occur to her to be jealous, but it would be extremely unpleasant if Georges found out about this. Her youngest son is extremely worried - in the end, Vincent is already an adult, and Olivier can rely on Edward's love. Meanwhile, Olivier is suffering: he needs Bernard and Edward, and he is forced to deal with Passavan. At a banquet about the release of the Argonauts, the mortally drunk Olivier makes a scandal, and in the morning tries to commit suicide. Edward saves him, and harmony reigns in their relationship. Passavan convinces himself that he has overestimated the beauty and ability of Olivier - the rogue Struvilu can do much better with the duties of a magazine editor.

Eduardo is unexpectedly visited by the forensic investigator Profitandier and asks in a kindred way to warn the prosecutor Molyneux: his son Georges was involved in a scandalous story with prostitutes, and now he got involved in a scam with fake coins. After painful hesitation, Profitandier starts a conversation about Bernard - Edward is convinced that this strong, confident man is most eager to regain his son's love. And Bernard brilliantly passes the baccalaureate exam. He so wants to share his joy that he hardly suppresses the desire to go to his father. In the Luxembourg Gardens he is an angel. Bernard follows him first to the church, then to a meeting of members of various parties, then to large boulevards filled with an idle indifferent crowd, and finally to poor neighborhoods where illness, hunger, shame, crime, prostitution reign. After hearing the story of Bernard about the night fight with the angel, Edward informs him of the visit of Profitandier Sr.

Meanwhile, disaster is brewing in the guesthouse. Children poison old Laperouse, and a company led by Geri steals a revolver from him. Struvilu has views of these schoolchildren: counterfeit coins go to grab, and Georges Molyneux got his father's love letters. Sofronitskaya informs Boris about the death of Broni - from now on, the whole world appears to the boy as a desert. At the instigation of Struvil, Leon throws a piece of paper at his desk with the words “Gas. Boris, who has already forgotten about his “magic”, cannot resist the temptation. Deeply despising himself, he agrees to pass the test for the title of "strong man" and shoots during the lesson - only Leon knew that the revolver was loaded. On the last pages of the diary, Edward describes the consequences of this suicide - the dissolution of the Azais guesthouse and the deep shock of Georges, who was forever cured of his admiration for Heridanisole. Olivier informs Edward that Bernard has returned to his father. Investigator Profitandier invites the Molyneux family to dinner. Edward wants to get to know little Kalu better.