When seventeen-year-old Bernard Profitendieu discovers an old love letter of his mother and realizes that he is an illegitimate son, he leaves a scathing letter for the man whom he considered his real father and runs away from home. He spends that night with his friend, Olivier Molinier. Olivier tells him of his Uncle Édouard, a writer, who will be arriving from England the following day and also of a woman with whom his older brother Vincent is involved.

The next morning, Bernard leaves before Olivier awakens. For a time he wonders what to do. He idly decides to go to the station and watch Olivier meet his uncle. That same morning Vincent visits his friend, the notoriously gay Comte Robert de Passavant. Vincent is disturbed over his affair with Laura Douviers, a married woman he met while both were patients in a sanatorium. Upon her release, she followed Vincent to Paris.

Édouard returns to Paris because of a promise to Laura. He knew her before her marriage and told her to call upon him whenever necessary. He is also looking forward to seeing his nephew Olivier, of whom he is very fond. He is so excited, in fact, that, after checking his bag, he drops his checkroom ticket. The meeting with his nephew, however, proves unsatisfactory. Unobserved, Bernard watches the meeting between the two. He picks up the checkroom ticket Édouard dropped and claims the bag. In it he discovers a large sum of money, which he quickly pockets; Édouard’s journal, which he reads without scruple; and Laura’s supplicating letter.

With no definite plan in mind, Bernard calls on Laura. Laura is disturbed by the young man who knows so much about her affairs, but his actions become understandable when Édouard arrives and Bernard admits the theft of the bag. He says that he stole it as a means of getting in touch with Édouard. Édouard is impressed with the young man’s impudent charm. When Bernard suggests that he might fill the role of a secretary, Édouard agrees. A few days later, with Bernard as his secretary, Édouard takes Laura to Switzerland. Bernard writes to Olivier in glowing terms about his new position. Olivier is jealous of Bernard, who, he believes, has taken his place in Édouard’s affections. He decides to take an editorial assignment offered to him by de Passavant.

In the meantime, Bernard falls in love with Laura. When he confesses his love, Laura shows him a letter from her husband, begging her to come back to him with her child and Vincent’s. She decides to return to him. Bernard and Édouard return to Paris. A letter then arrives from Olivier to Bernard. He is in Italy with de Passavant, and he writes complacently about the wonderful journal they intend to publish. Bernard shows the letter to Édouard, who fails to realize that the letter disguises the boy’s real feelings of jealousy and hurt.

Although still serving as Édouard’s secretary, Bernard enrolls in the Vedel School and is living in the Vedel household. The Vedels are Laura’s parents and Édouard’s close friends. Édouard is particularly fond of Rachel, Laura’s older sister, and it distresses him to see that she is devoting all of her time and energy to managing the school. Bernard tells Édouard about some children, including George, Olivier’s younger brother, who are engaged in some underhanded activities. The boys, as Bernard is soon to learn, are passing counterfeit coins.

Olivier returns to Paris to get in touch with Bernard. The meeting between the two is strained. As they part, Olivier invites Édouard and Bernard to...