As the mother of a 16-year-old girl, Anne Joubert is happy in her job and in her marriage. But when she learns that her daughter is using drugs, everything she took for granted suddenly collapses. She is forced to begin a major overhaul of her life.

To strengthen their couple on the verge of breaking up, Bastien and Elise set off for a hike in the woods. A few years later, Bastien has become cynical and dark. He has a relationship based on voyeurism and sadomasochism with a woman called Sarah. One night, by continually pushing their experiences farther, the young woman is shocked and decides to distance herself from her lover. She then tries to get rid of him but he ends up losing his temper and imposing her the narrative of his hike with Elise. At first perplexed as for the intentions of the man who holds her back, Sarah is gradually overwhelmed with awe when the story falls into madness and Elise and Bastien, lost in the middle of nowhere have to face a threat that is bigger than their faltering romance

Sprigs of broom around a murder victim suggest an ancient legend.