The Bridesmaid (La Demoiselle d'Honneur)

Philippe (Benoît Magimel) meets and instantly falls in love with Senta Bellange (Laura Smet), who is a bridesmaid at his sister's wedding. At first he is drawn in by her mysterious nature and intense passion, but as time passes, he finds her unpredictable behavior increasingly troubling. When Senta asks Philippe to commit a horrible, violent act as proof of his love for her, he is unsure whether it's one of her delusions or if she really expects him to act.