Twelve-year-old Anaïs and her fifteen-year-old sister Elena are enjoying a summer getaway with their parents in the picturesque French coastal town of Les Mathes. Feeling confined and disinterested in their vacation home, the two sisters venture into town, engaging in candid discussions about their experiences with relationships and their thoughts on virginity. Despite Elena’s conventional beauty and her history of promiscuity, she maintains a personal vow to reserve her first sexual encounter for someone who genuinely loves her. In contrast, Anaïs, who is more self-conscious about her weight, prefers to lose her virginity to a man she does not harbor romantic feelings for.

Their excursion leads them to a quaint café where they meet Fernando, an Italian law student full of charm and charisma. The dynamics between the sisters take an unforeseen turn when Fernando stealthily enters their room later that night for a rendezvous with Elena. Anaïs, however, is awake and becomes a reluctant witness to their intimate encounters. As Elena grapples with the emotional weight of her decision amidst discussions about Fernando’s previous romantic involvements, she initially consents to sleeping with him. However, she retreats at the last moment, only to be subjected to increasing pressure from Fernando. Frustrated, he tantalizes her with threats of seeking out another woman to fulfill his needs. Ultimately, Elena is coerced into anal sex as a so-called “proof of love,” an experience that is undeniably painful and emotionally wrenching for her.

As dawn breaks, Fernando requests oral sex from Elena before his departure, but Anaïs, exhausted from the events of the previous night, intervenes with a demand for peace. The following day unfolds with the three of them heading to the beach, where Anaïs finds solace in the ocean, dressed in her new attire and singing softly to herself, while Elena and Fernando wander off together, lost in their own world. When the sisters reflect on fond memories from their childhood back at the house, Elena reveals that Fernando has given her an engagement ring during their beach outing. This revelation sows seeds of doubt for Anaïs, who cannot shake her skepticism about Fernando’s true intentions.

As night descends, Elena succumbs to Fernando’s advances and loses her virginity, leaving Anaïs to silently weep in the shadows, heartbroken and isolated on the other side of the room. The story takes a dark turn when Fernando’s mother arrives at the vacation house, demanding the return of the engagement ring, which turns out to be part of a collection of heirloom jewelry that she retains from past lovers. Upon discovering Elena and Fernando’s relationship, she reacts furiously and decides to drive back to their Paris home. During the journey, fatigue sets in, prompting her to rest at a roadside stop. Tragically, their lives are shattered when a man attacks them; he viciously smashes the windshield, resulting in Elena’s murder, while their mother is also brutally assaulted.

In a horrifying turn of events, when Anaïs manages to escape the chaos, the attacker takes her deep into the woods, where she is subjected to a horrific sexual assault. The aftermath of this trauma becomes even more distressing when law enforcement arrives. Despite her harrowing ordeal, the officers dismiss her claims of rape, specifying that she contradicted herself during questioning. As Anaïs begins to internalize a growing mistrust of men throughout this chilling story, she finds her voice to challenge their assumptions, brutally aware that her size leads them to disbelieve her harrowing statements. The psychological trauma and the unfolding tragedy leave Anaïs confronting a world steeped in betrayal, loss, and unwavering fears in the wake of her family’s devastation.