A love triangle between 23-year-old Emma (Anna Karina), her older boyfriend (Georges Descrières) and the younger man (Jacques Perrin) she meets while on vacation by herself.

Patrice's good looks have made him a consummate womanizer but they also helped him win the heart of Juliette, the daughter of Blanche Eroli, an influential Parisian clothes designer. The latter doesn't want him as a husband for Juliette and would prefer to see her married to Vincent, her right hand man. To this end she offers Patrice a juicy check if he agrees to leave Juliette. He accepts the deal and leaves for the Riviera, where he discovers love in the person of pretty Caroline. But Juliette, who does not love Vincent, traces Patrice as far as Nice. Soon afterwards her dead body is found lying on her former fiancé's bed...