Wealthy bourgeoise Frédérique (Stéphane Audran) is plucked off the street by Parisian pavement artist Why (Jacqueline Sassard), who whisks her away to off-season Saint-Tropez for a life of idle decadence in the company of her raffish friends.
There, they meet architect Paul (Jean-Louis Trintignant), whose initial interest in Why is cruelly exploited by a jealous Frédérique for her own selfish ends.
But Why is no longer the virginal innocent that she was at the beginning of the film, and it's at this point that Claude Chabrol's film stops being an elegant comedy of manners and starts turning the psychological screws with the millimetre precision characteristic of the man often dubbed the French Hitchcock.