Dominique Marceau is on trial for the murder of Gilbert Tellier. The counsels duel relentlessly, elaborating explanations for why the pretty, idle and fickle girl killed the talented and ambitious conductor freshly graduated from the conservatory. Was it passion, vengeance, desperation, an accident? The acquaintances of Gilbert testify, as well as Dominique's former lovers, and her sister, Annie, the studious violin player engaged to Gilbert. The evidence they give progressively paints a more finely-shaded picture of the personalities of Dominique and Gilbert, and of their relationship, than the eloquent and convincing justifications of the counsels.
Gilbert becomes infatuated with Dominique, though they are polar opposites in terms of values and personality. Eventually, they begin a turbulent relationship, during which Dominique takes an uncharacteristically long amount of time to consent to Gilbert's sexual advances, impulsively sleeping around with other men in the meantime. Gilbert is jealous and frustrated but remains committed to Dominique. After they finally consummate their relationship, he proposes to her but she refuses. They move in together, but their differing lifestyles lead to further contention, and Dominique cheats on him, after which he beats her. The landlady evicts Dominique from Gilbert's flat, leading her to take a job at a restaurant to pay her own rent. Gilbert becomes suspicious that Dominique is involved with the restaurant owner, Toussaint. This leads to an emotional breakup, as Dominique insists nothing is going on with Toussaint while Gilbert refuses to believe her.
- excerpt from wikipedia