Spring 1963. French countryside. Hippolyte (20) and Delphine (25) are two sisters from a provincial bourgeois family. They are secret incest lovers. France, their mother, combines an engagement for Hippolyte with the wealthy Vincent. Coming back from a short trip to Paris, Delphine finds out that France has planned Hippolyte's marriage by the end of the summer. This sparks a conclusion that their love is the most important thing, no matter who comes in their way, even if it is their evil mother.
—Les Fleurs du Mal