Pierre Lachenay, a prominent middle-aged writer, lecturer, and editor of a literary magazine, successfully makes his way to Paris-Orly Airport to catch a flight to Lisbon. Upon disembarking, he is greeted by a group of enthusiastic photographers, eager to capture him in a moment with Nicole, a charming stewardess who piqued his interest during the flight.
After delivering a well-received lecture titled "Balzac and Money" to a sold-out audience, Pierre returns to the hotel where Nicole also happens to be staying. Excited to see her, he shares an elevator ride and cleverly notices her room number on a keycard. Taking a bold step, he calls her to invite her out for a drink. Initially, she declines due to the late hour, but moments later, she calls him back, and they agree to meet the next evening—despite Pierre having original plans to catch a flight at noon.
Their date unfolds in a cozy bar, where they engage in deep conversation until the sun rises. The chemistry is undeniable, leading them back to Nicole's room for an intimate encounter. After the passionate night, she discreetly slips him her phone number on their flight back to Paris. However, when Pierre attempts to reach her that evening while entertaining guests at home with his wife Franca of fifteen years, Nicole is unavailable.
Determined, Pierre finally connects with Nicole the following day, setting the stage for a series of clandestine meetings. As their secret romance blossoms, Pierre starts crafting excuses just to see her at the airport between her flights. Eventually, they plan for an overnight stay, opting for a hotel instead of her apartment due to the potential risks of being discovered. They attempt to enjoy a night out at a nightclub where Pierre admires Nicole dancing, but their plans to check into a hotel unravel as they both feel increasingly uncomfortable with the situation.
Pierre then proposes a getaway to Reims and to his delight, Nicole eagerly accepts. They drive from Paris to a secluded hotel, with Pierre foiling obligations including a friend Clément’s dinner that threatens to intrude upon their time together. As the evening unfolds, Nicole is left feeling abandoned after Pierre has to attend to other commitments, diminishing her spirits when he finally shows up to apologize.
Their romantic escapade continues as they reach a charming inn. However, trouble looms on the horizon when Pierre's phone call to Franca exposes his deception—she's aware that he’s lying. Upon returning home, tension escalates as Franca accuses him of infidelity, leaving Pierre grappling with the situation that could lead to separation. In the emotional turmoil that follows, Pierre and Franca share an intimate moment, filled with confusion and underlying affection, but ultimately, he decides to leave her.
As the story spirals further, Franca reveals her determination to initiate divorce proceedings after a heated confrontation with Pierre. The emotional back-and-forth ensues, characterized by anger and longing, culminating in an unexpected physical encounter. Meanwhile, Franca’s friend Odile grows concerned for her mental state, fearing self-harm, prompting her to dispose of any harmful items.
Pierre experiences discomfort when out with Nicole, leading him to reflect on the strains in his life that keep him distant from his daughter. Shortly after, an unsettling turn of events occurs when Nicole expresses her need to part ways, realizing their incompatibility. The tension reaches its climax when Franca, having discovered incriminating photographs, confronts Pierre at a restaurant and, in a shocking act, shoots him with a shotgun before surprisingly sitting down and smiling, marking a twisted end to a love story laden with betrayal and unresolved emotions.
