Private detective Claude Chavasse (Maurice Chevalier) has a client who wants to kill another of his clients. It’s a tough break, especially since target Frank Flannagan (Gary Cooper) is not only a philanderer but also incredibly wealthy.
After becoming infatuated with the would-be victim, young cello student Ariane (Audrey Hepburn) foils the hit and begins a love affair with the worldlier Flannagan. To keep up, Ariane pretends to be more experienced than she is by recounting sexual escapades she’s seen in her PI father’s files.
In Love in the Afternoon, Billy Wilder sets up a world of cads, men who admire cads and innocent women who are all too often used by cads, however soon enough the tables are turned. Ariane soon becomes the character with the most to lose, but also the character with the most control.