Stuck in traffic jams, in pouring rain, a young 27-year-old graphic designer named Jade receives a call from a client asking her to work on a new project as soon as possible. The young woman's attention is elsewhere, and she is seized by flashes that remind her of an esoteric ritual she recently performed with her friend, Julie. Invited at the time by Julie to come and recharge her batteries in Brittany, Jade had lost all inspiration. She could no longer work and fell into a deep depression. It was then that Jade learned of a powerful but forbidden ritual. The ritual of La Croix, linked to the Breton lighthouse of the same name. Julie tried to stop her, but ended up doing it with her friend. During the session, the desperate artist implores the return of lost inspiration, and has herself branded with the ritual's seal: a circled cross. But for some time now, strange things have been happening to her. Caught up in her thoughts, still at the wheel, she collides with a young woman with a hidden face, also marked with the Cross. While looking for the street name to inform the emergency services, Jade comes across an old woman at her window, staring at her menacingly. Panicked, Jade flees. Little by little, Jade comes to understand what kind of ritual she's really been performing, and what kind of old lady has seen her at the window.