In 1938 Paris, Marcello Clerici, Jean-Louis Trintignant, finalises his preparations to assassinate his former university professor, Luca Quadri, leaving his wife, Giulia, in their hotel room. After receiving a call, Marcello is collected in a car driven by his subordinate, Special Agent Manganiello.
A series of flashbacks follow, revealing a fragmented portrait of his life and psyche. They show Marcello discussing with his blind friend, Italo, his hopes of marrying, and his attempts to join the Fascist secret police, alongside visits to his parents in Rome: a morphine-addicted mother lingering in a decaying villa and a father residing in an insane asylum. The memories deepen the sense that Marcello has long been shaped by a harsh, morally ambiguous world.
In a pivotal 1917 flashback, Marcello is a boy taunted by schoolmates until Lino, a chauffeur, intervenes. Lino reveals a pistol and then sexually assaults him. Marcello partly resists, then grabs the weapon and fires, first at the walls and then at Lino, before fleeing, convinced that he has committed murder. This moment haunts him across decades, planting the seeds of a conscience shaped by fear, guilt, and a craving for control.
Another memory centers on a conversation with Giulia about confession, even though Marcello is an atheist. He hopes to win her Roman Catholic parents’ approval for their marriage, so he agrees to confess. In the priest’s eyes, Marcello admits to sins such as the rape and presumed murder of Lino, premarital sex, and a perceived lack of guilt. He tells the priest that he prioritizes a normal life and a traditional marriage with children, a desire that contrasts with the darker impulses he harbors. The priest is shocked, but absolves him once he learns that Marcello works for the Fascist secret police.
The mission accelerates in Ventimiglia, where Fascist officer Raoul orders him to eliminate Quadri, a staunch anti-Fascist intellectual living in exile in France. To disguise the operation as a honeymoon, Marcello takes Giulia to Paris, intending to carry out the assassination without arousing suspicion. The trip unsettles him, yet opportunity and temptation push him forward.
While visiting Quadri, Marcello is drawn to Anna, Quadri’s French wife, and begins pursuing her. Anna, aware of Marcello’s dangerous Fascist sympathies, responds to his advances and forms a complex bond with Giulia as well. The two women dress in lavish styles and accompany their husbands to a dance hall, where Quadri’s intellectual integrity and Marcello’s loyalties are put to the test. Manganiello, who has been tailing Marcello, remains skeptical of his true intentions throughout.
Marcello secretly returns the gun he has been given and feeds Manganiello the location of Quadri’s country house in Savoy, where the couple plans to retreat the next day. Despite Marcello’s caution and Giulia’s warning, Anna chooses to accompany her husband into the countryside, drawn by the allure of the dangerous liaison and the prospect of freedom.
On a secluded Alpine road, Quadri and Anna are fatally shot by fascist agents. Anna, horrified, watches as the killers close in. When the assailants shift their attention to her, she runs toward the car behind for help and discovers Marcello in the back seat, realizing his betrayal. She screams and flees into the woods, pursued by the agents. Marcello watches as she is shot dead; Manganiello, disgusted, steps away to light a cigarette, chastising Marcello for his cowardice in not shooting Anna when she came toward the car.
The years move forward to 1943, amid Mussolini’s resignation and the collapse of the Fascist regime. Marcello now has a daughter with Giulia and appears settled in a conventional life. One night, as crowds celebrate the fall of Mussolini, he strolls through Rome with Italo and overhears two men flirting, recognizing one as Lino, who survived the earlier assault. A shattering awareness dawns: he never killed Quadri, and the burden of that long-held guilt intensifies. He begins to denounce Lino as a Fascist, a homosexual, and the murderer of the Quadris, while also turning on Italo as a Fascist. As an anti-Fascist crowd sweeps past, taking Italo away, Marcello sits beside a small fire and stares at the lingering memory of Lino’s companion—now seen as a naked young man nearby—an unsettling image that underscores the hollowness of the world he has inhabited and the price of his choices.
