Brian Bloom, portrayed by Anton Yelchin, is a 24-year-old writer striving to establish himself in the bustling streets of New York City. His life takes an unexpected turn when he becomes fascinated by the mysterious Arielle Pierpont, played by Bérénice Marlohe, a 33-year-old French woman who carries her own secrets. Their connection ignites with electric chemistry, and despite sensing that their entanglement is deeper than it appears, they are unable to resist their mutual attraction.
During their second encounter, Arielle shares the complex dynamics of her marriage to Valéry, depicted by Lambert Wilson, a diplomat nearly twice her age. She divulges the unusual arrangement they have regarding extramarital affairs: an exclusive window from 5 p.m. to 7 p.m. on weekdays. This revelation shocks Brian, who grapples with the morality of such an arrangement and initially decides it doesn't suit him. Nevertheless, Arielle tantalizes him with an invitation to meet again at their original meeting spot every Friday.
The pull of their forbidden romance proves irresistible, drawing Brian back into Arielle's world. They begin to meet regularly in the hotel room that transforms into their intimate refuge. However, Valéry is not oblivious to Brian's involvement and takes it upon himself to confront the situation.
In a pivotal dinner encounter, Brian meets Arielle’s children and her lover, Jane, played by Olivia Thirlby, a 25-year-old editor shrouded in her own enigma. This meeting ignites a series of emotional confrontations that test the limits of their relationships.
As tension builds, Brian is introduced to Arielle's family, including her parents, Sam and Arlene, portrayed by Frank Langella and Glenn Close, respectively. Sam's stern disapproval starkly contrasts with Arlene's unconditional acceptance of Arielle's choices, amplifying the complexities surrounding their love affair and leaving Brian with a tumult of emotions and questions.
The narrative escalates when Brian earns an invitation to receive an award for his short story, where Arielle, Valéry, Jane, and Brian's own parents join him in celebration. At this event, Jane reveals that their mutual friend, Galassi, has significant interest in publishing Brian's work.
In a moment rife with emotion, Brian proposes to Arielle, presenting her with a ring and asking her to marry him. She joyfully accepts, setting plans to reunite at their hotel sanctuary the following day. Unbeknownst to him, Valéry has been observing from the shadows, harboring a smoldering anger. His confrontation with Brian culminates in a slap and a check for $250,000, which he claims is intended to ensure that Arielle has the life she deserves. With that, Valéry exits, leaving Brian to grapple with the fragile nature of their relationships and the uncertainties that loom ahead.
The aftermath events spiral as Brian receives a heartfelt letter from Arielle via the hotel doorman. Her words resonate with genuine love and regret as she confesses that, despite her feelings for him, she cannot abandon her family. The note implicitly urges him not to reach out again, solidifying the heart-wrenching decision.
Meanwhile, Jane's connection with Valéry reaches its breaking point, amplifying the strain on Brian and their shared friendship. Eventually, as time moves forward, Brian's writing endeavors come to fruition with the publication of his debut novel, marking a significant milestone in his career.
Years later, Brian, now accompanied by his wife, Kiva, and their spirited two-year-old son, wanders the city streets. Fate intervenes when they unexpectedly cross paths with Arielle, Valéry, and their now-teenage children outside the iconic Guggenheim Museum. This encounter brims with nostalgia and unresolved feelings, as Valéry inquires about Jane's life, to which Brian openly shares her newfound happiness.
Yet, the subtle hint of Arielle preserving the ring he once bestowed upon her reveals her lingering emotional connection to Brian, hinting at a love that may never fully fade away.
