Martin Sauvagnac, Alexis Loret grows up in Cahors with his hairdresser mother, Jeanine, and her taxi-driver lover, Said. He is the illegitimate child of Victor Sauvagnac [Pierre Maguelon], a successful businessman whose world feels distant to him. Against the child’s wishes, Jeanine sends Martin to live with Victor, who is already married and has three older sons. The move is far from happy, and Martin quickly clashes with his brash, cold father.
Ten years later, just after Martin’s twentieth birthday, he flees his home following Victor’s death. He wanders across the countryside and even tries to drown himself, only to reappear weeks later at his half-brother Benjamin Sauvagnac’s apartment in Paris. Mathieu Amalric is a struggling actor who shares his space with his best friend, Alice, a violinist in a local tango ensemble, Juliette Binoche. Benjamin is more outgoing than Martin and forms a close, platonic bond with Alice, while Martin rapidly finds success as a sought-after model, a turn of events that unsettles everyone around him. Alice, grappling with the private grief of losing her gifted sister years earlier, is initially wary of Martin, and she remains emotionally unsettled as his attention grows into an all-consuming fixation.
Alice’s initial resentment gives way to a dangerous attraction, and the two begin a volatile, passionate affair. They leave behind Paris and travel to Granada, Spain, for a modeling assignment, where Martin’s mood grows more unpredictable and self-centered. When Alice discovers she is pregnant, his decline accelerates, culminating in a nervous breakdown that leaves him in a coma. Doctors diagnose the condition as psychosomatic, and to help him recover, Alice rents a cabin by the sea in southern Spain. Martin spends hours swimming each night, haunted by the memory of his father’s death.
A flashback reveals Victor Sauvagnac’s fragile relationship with his sons. The family dynamics fracture as François and Frédéric—the two eldest brothers—argue during a tense reunion over the family business, ending in a fist fight. Martin’s decision to leave for Paris after an argument with Victor leads to a fatal push down the stairs, and Victor dies. Unable to live with what he has done, Martin eventually runs away and hides from the consequences.
Back in the present, Martin declares himself unable to bear the weight of his crime and admits himself to a mental institution. Alice travels to Cahors to confront the Sauvagnac family and befriends Martin’s mother, but Lucie, Victor’s widow, remains outwardly hostile, while Frédéric Sauvagnac, the town’s mayor, is openly antagonistic. Benjamin returns to the town in an effort to protect his brother’s memory, and the siblings slowly begin to mend their rift. Lucie ultimately chooses to inform the authorities about Martin’s culpability, and he confesses, surrenders, and is sent to prison. Alice, determined to go on with her life, decides to have her baby. She is seen playing her violin at a wedding, while Martin, in prison, writes a letter to Alice that suggests he has found a measure of peace at last.
