When Marc (Benoît Poelvoorde) misses the last train home from the small town where he works and is forced to find a hotel, he by chance meets Sylvie (Charlotte Gainsbourg) in a local bar. To both their surprise, Marc and Sylvie hit it off and plan for a romantic rendezvous in Paris, but it does not go as expected. Sometime afterwards, Marc meets Sophie (Chiara Mastroianni) and the couple falls deeply in love. They start living together and plan on getting married, but what Marc is unaware of is that Sophie and Sylvie have more in common than just him, they are also sisters.