One winter night, Nathalie Weber, a writer in need of inspiration, regains her ability to imagine a story and lets the words run on the paper until dawn. Hundreds of kilometers away, at the same time, in a Romanian orphanage, 16-year-old Iona takes her own life. When they wake up, in their isolated chalet in the mountains, Nathalie announces to Marc, her husband, that the romantic breath has returned. While Marc goes to pick up his parents at the airport, Nathalie begins the preparations for Christmas lunch, hoping that Alice, their 16-year-old daughter, will help her. Suddenly assailed by images of the character from her new novel, who has the features of Iona, Nathalie hastens to write them down. A little later, from a window, she sees a strange silhouette and receives a call that terrifies her.

Fifteen years earlier, Nathalie and Marc had come to look for Alice in an orphanage in Romania. Nathalie hadn't recognized the infant that the director had presented to her during a first visit. Taken by a feeling of unease, she had entered by chance into a secret room where she had discovered, with horror, dirty children, left to their own devices, and had recognized Alice among them. But a mysterious force pulled her out of the room. Now, when it's time to celebrate Christmas, the mother and her teenage daughter find themselves alone, snowbound in their chalet cut off from the world.

Iona's body is transported on a sled in the blizzard before being buried. Increasingly disturbed by strange noises, anonymous calls and videos that show her with her husband in private, Nathalie walks the halls of the huge chalet in search of her daughter. She discovers her serenely seated facing the hearth and orders her to close doors and shutters, before rushing into her office where she barricades herself. While Alice, frightened by her mother's behavior, bangs desperately on the office door, Nathalie receives a new video whose content will prove to be premonitory.