Juliette (Jeanne Moreau) and her husband, Valmont (Gérard Philipe), are an attractive, much-gossiped-about couple who help one another find lovers on the side in order to keep their own relationship interesting. Neither Juliette nor Valmont has ever taken these dalliances seriously, until Juliette's newest beau ditches her for the chaste Cecile (Jeanne Valerie). Scorned, Juliette enlists Valmont to seduce Cecile and ruin her good name, but the plan results in betrayal and violence.