Olivier, a handsome but callow and moody young student, picks up an enthusiastic actress during a theatre rehearsal, and is introduced to her acquaintances -- a group of jaded rich kids who spend their time storming around the Riviera harassing passersby, throwing wild parties and following all the latest trends. When sexy Elke gives him the eye, he leaves the actress in the lurch and joins the gang for a decadent party aboard a yacht. However, Elke's wanton ways and Olivier's inexperience do not mesh, and in a snit, he accidentally sets the yacht afire. The gang wreaks its vengeance by luring him into a dangerous contest of bravura on a construction site.

Eloi is a twenty-year-old secondhand goods dealer who does his job without particular enthusiasm. He has a girlfriend, Nénette, but immature as he is, he feels just as happy in the company of Fortunée, his young sister, whose little girl's games he shares as often as he can. The three of them live with Eloi and Fortunée's grandmother, nicknamed by all the "Queen of the Flea Market". In possession of a mirror of Venice, Eloi decides to present it to Dormoy, an antique dealer who keeps up shop in the fashionable districts of Paris. On that occasion Eloi meets and falls in love at first sight with Dormoy's rich mistress. The latter, half-moved, half-consenting, does not discourage him.

Lucien, a modest engineering student, discovers that his steady girl friend Mireille is using him to cover up her dates with Mario, an older man. Lucien wanders about the streets of Paris and meets Joëlle, a sophisticated teenager who supports herself with a job in a sleazy nightclub. It is late when they meet, and Joëlle invites Lucien into the club and demonstrates her stripping act to her one-man audience. A feeling of rapport develops as they go from place to place seeking entertainment; in the morning the two discover they have fallen in love. Mireille learns of the romance and, on a bet, plots with Philippe and other friends to break up the affair. Neither Lucien nor Joëlle, however, succumbs to the propositions of Mireille and Philippe. Later at a nightclub, Mario gives the appearance of seducing Joëlle. Enraged, Lucien rushes at him and they fight. Lucien is reunited with Joëlle--he has learned of the complexities of love, and she has acquired from him a sense of stability.

Young provincial Charles arrives in Paris to stay with his cousin Paul while studying law. Paul is a decadent, bohemian pleasure-seeker who shows the meek, diligent Charles the thrills of city life. When Charles falls for Florence, one of Paul's acquaintances, relationships begin to shift.