20 years ago, Fanny Legoff was accused of being responsible for the disappearance of her best friend, Laura Perrier, in the forest of Brocéliande. Laura's body was never found. Since then, Fanny has rebuilt her life in Paris, where she has become a biologist. Until the day Fanny receives a strange package... which contains a billhook covered in Laura's blood. Who sent her this billhook? For what purpose? Unable to warn the police without incriminating herself, Fanny decides to return to Brocéliande and get to the bottom of the truth.