Leon Mortier, a wealthy publisher, whilst driving through the forest one day, stops when he sees Lulu walking down the long narrow road. She gets into the car. Leon is amused and intrigued by her. When he pulls off, suddenly out of nowhere a man appears in front of the car and Leon accidentally hits him. He decides to take them both home to recover. Leon falls madly in love with Lulu. Both Lulu and the man stay on with him in the house. Lulu's behavior is unpredictable. Leon becomes suspicious and paranoid about her. As he begins to suspect that his friends are being unfaithful with Lulu, he decides to throw a dinner party with some of his closest friends. During the dinner he wants to confront them with their infidelity and expel them all from his life with Lulu. But when he discovers his son in the arms of Lulu, he decides also to get rid of her, a plan which backfires in a most unexpected way.