Henry de Sacy, inveterate Don Juan, learns that he will inherit a million euros from his old aunt, on condition that he gets married within the year. As he refuses to depart from his love of women, his friend Norbert, a lawyer, offers him to marry a man. Thus he would respect his aunt's last wishes without losing his freedom. Seduced, Henri offers this unusual contract to his friend Dodo who is single and unemployed. But this marriage for the better will quickly turn into a nightmare...