Marilou and Philippe prepare for their future retirement in Portugal. But their daughter separates and a whole procession of solicitations falls on them.

Two couples, Pierre and Aimée, Éric and Pénélope, all share four years of friendship without cloud. Only concern, Penelope and Pierre have become lovers ... The situation becoming untenable, they decide to break. But after a final night of passionate love, fate plays a trick on them: Peter and Penelope each wake up in the body of the other! To protect their secrecy, they each find themselves having to live the life of the other. This is the beginning of the complications ...