Fanny Legoff, a recognized and admired biologist, has lived in Paris for more than fifteen years, after leaving the Brocéliande university during her studies following the disappearance of her best friend Laura, for which she had been suspected. When Fanny receives a package containing a billhook covered in dried blood and a letter accusing her once again of being responsible for Laura's disappearance, she decides to return to her native region, fifteen years after the tragedy.