The action takes place at the turn of the 19th Century. Adolphe (Stanislas Merhar) is a carefree, somewhat jaded 22-year-old, scion of a preeminent aristocratic family, with a very promising political career ahead of him. To Adolphe, love means conquest, and since he is bored, love is a good pastime. At a soirée given by the Count (Jean Yanne) in his sumptuous castle, Adolphe sets his eyes on the beautiful Ellénore (Isabelle Adjani), a young widow, ten years his elder, mother of two children. She also happens to be the Count's mistress. Adolphe falls in love with Ellénore, for lack of a better thing to do. At first, Ellénore resists Adolphe's feverish advances. He insists, becoming an overwhelming presence (and nuisance) in Ellénore's life. Eventually, she surrenders. Soon after, the novelty of this adventure wearing out, Adolphe tries to liberate himself from his new lover, who has become a burden in his life, an obstacle to his freedom. However, he cannot bring himself to altogether sever his relationship with Ellénore, as the idea of making her suffer is to him unbearable.

Ellénore loses everything as she tries desperately to "hang onto" her lover: her children, the Count's protection, her status in society. For his part, Adolphe's life is in limbo, as he is unable to break once and for all with his now dying love affair. He offends his father, who demands his return to a more conventional life, and he abhors his own indecisiveness, his inability to end his love affair and regain his freedom. What follows is the fallout of an obsessive relationship: unbearable guilt, accusations, and poison letters of recriminations between the two parties. Eventually this emotional charade ends up in death and misery.