Philippe and Sylvie bring home a small container they found on the way from school and strange things start happen...

Justin, a lyricist by trade, and his friend Pierre, a composer, lead a bohemian life in Paris. Justin thinks his mother Josefa is richer than she appears, and decides to swindle her out of three million centimes by using Pierre as an intermediary in a case involving an insolvent check. Josefa uncovers the ruse and refuses to help her son. However, Pierre has discovered the identity of his friend's father, who had been unknown to him for twenty years. With the help of Justin's mother, the two friends do everything they can to extort the son's missing three million centimes from his ashamed and repentant father.

As Dominique Marceau is being tried for the murder of Gilbert Tellier, accounts by different witnesses paint a picture of the kind of relationship the two used to share.