Two couples, Pierre and Aimée, Éric and Pénélope, have been the best of friends for the last four years. A tiny detail: Penelope and Pierre became lovers, and when the situation became untenable, they decided to break-up. But after a final night of passionate love, fate plays a trick on them: Peter and Penelope each wake up in each other's body. To protect their indiscretion, they find themselves having to live the life of the other. But for how long can they can keep it a secret?