Lucas, a 17-year-old student at a boarding school in Chambéry, experiences a series of profound and emotionally charged events following the tragic death of his father. The story begins with the shocking news that his father has been involved in a car accident, leading to his return home where he reunites with his mother, Isabelle Ronis. During the funeral, Lucas is secretly visited by his high school sweetheart, Oscar, which adds a layer of complexity to his grieving process.
At home, the family gathers for a dinner filled with intense political discussions. During this uncomfortable meal, Lucas suggests that his father didn't believe in God, hinting at deeper issues within their family. Tensions escalate, prompting Quentin, Lucas's older brother, played by Vincent Lacoste, to take Lucas outside to calm down. A heated argument ensues, with Lucas accusing Quentin of abandoning his family for a glamorous artistic lifestyle in Paris and suggesting Quentin's love for their family is lacking. The brothers have a brief but meaningful fight, which they quickly reconcile.
Lucas spends the night at Oscar’s house, where they share an intimate moment. The following morning, the two head to the cemetery to visit their father's grave. During this visit, Lucas wrestles with feelings of shame, believing that his father was disappointed in his sexuality and that he would not succeed in life. Quentin, however, passionately counters this view, asserting that their father loved his children unconditionally, regardless of their differences.
Eager to escape his grief, Lucas travels with Quentin to Paris. There, he develops a close bond with Lilio, a sensitive artist and Quentin’s roommate, played by Erwan Kepoa Falé. Lucas spends his first day exploring the city on his own, even engaging in an anonymous one-night stand, which reflects his desire for connection and escape. That night, he sleeps next to Lilio, and they enjoy a jog together the next morning.
As Lucas spends more time with Quentin and explores Paris, he begins to feel restless. When he returns to his apartment, he discovers Lilio meeting a client. In a moment of impulsiveness, Lucas secretly contacts the same client, offering his services. Later, Lucas and Lilio visit a restaurant owned by Lilio's mother, where they share conversations about love and sing karaoke, creating a fleeting sense of happiness. Their friendship becomes complicated when Lucas tries to kiss Lilio on the train ride home, only to be rejected.
Tensions escalate as Lucas confronts Lilio's client, demanding honesty about their meeting, but Quentin intervenes angrily when he finds out. Despite Lucas’s desire to stay in Paris, Quentin insists he go back home, warning him not to let his grief destroy him.
Back at home, Lucas and Isabelle pay tribute to his father by placing flowers at the roadside. Struggling with grief and feelings of shame, Lucas suspects his father's accident might have been a suicide, which prompts his mother to slap him in response. Overcome with pain, Lucas makes a desperate decision—he vows silence and then harms himself by slitting his wrists with glass from a broken mirror, signaling his crisis.
Lucas is admitted to a psychiatric hospital, where he begins to slowly heal. He finds solace in jogging, listening to music, and attending church, while also managing his grief privately. During his time in the hospital, he is visited by Isabelle and Quentin, who support him. Meanwhile, the patients and staff watch news reports about climate legislation in France, adding a backdrop of societal concern to their personal struggles.
A turning point occurs when Lilio visits Lucas, offering empathy and friendship. They share a jog to the train station and part ways with a heartfelt hug. Eventually, when Isabelle visits Lucas at the hospital, he begins speaking again, expressing his desire to leave and move forward. His mother, after some initial anger, finally accepts her husband's death, allowing herself and Lucas to begin living again. This shared acceptance marks a hopeful step toward healing, symbolizing the possibility of renewal after profound loss.
