One night in Paris, Esther, a marketing professional, attends a house party with colleagues. In the backyard she injures her leg on exposed industrial supplies. The accident goes unnoticed at first, and it isn’t until later, while she inspections an upstairs bathroom, that she realizes the injury. After the party, a doctor patches her up and wonders why she didn’t feel the hurt initially; Esther seems indifferent to any cosmetic damage.
The next day, while taking a bath, she becomes fascinated by the folds of skin around her thigh. Her boyfriend, Vincent Laurent Lucas, notices the injury and grows concerned about her numbness. He tests her sensitivity by lightly touching her arm when she isn’t looking. She reacts normally, but their exchange grows tense and they quickly reconcile.
At work, Esther impulsively rushes into a filing closet and cuts herself again with a scrap of metal. She tells her friend Sandrine, Léa Drucker, that she has just cut herself and laughs it off. Sandrine invites Esther to stay over for the night. There, as Esther takes a shower, Sandrine notices the cuts on Esther’s leg. Esther remains indifferent to Sandrine’s concerns. Later, when they talk about work, Sandrine reveals her own ambition to move up in the company.
The following day Esther informs Sandrine of a promotion, while Esther later shares with Vincent Sandrine’s jealousy; he is more worried about the new injuries to Esther’s leg. Esther asks him to stop questioning her, and he reluctantly agrees as they discuss moving in together.
During a dinner with her supervisor and important clients, Esther’s arm moves on its own and eventually detaches from her body. She begins to stab at it with a steak knife, excuses herself from the table, and carries the knife to continue cutting and gnawing at her arm. She checks into a hotel and continues to cut and chew at her hands and thighs, leaving large bite marks. She deliberately crashes her car in the woods to explain the injuries. Vincent meets her in the ambulance, Laurent Lucas inspecting her cuts and growing suspicious.
Back home, they discuss moving in after she heals, while the supervisor berates her for the behavior at dinner. While walking to work the next day, Esther purchases a camera and a new knife. She goes to another hotel and begins to cut at her flesh again, including her face. She asks a pharmacist about preserving a piece of her skin that she cut out. Back at her hotel room, she calls her work to apologize for her unexplained absence. She also leaves a phone message for Vincent telling him that she will not be home that night. The next morning, she wakes, inspects the now-shriveled piece of skin, places it in her bra, and quickly leaves the room. A subsequent shot shows Esther still lying on the bed, staring vacantly into the camera. The shot fades to black.
