Maxime Rivière, a friend of Commissioner Bachert, is the victim of a recurring nightmare concerning the murder of the Tibetan monk. Astrid makes the connection with the unsolved murder of the llama Tulku Lingpa, on May 20, 1996, in a monastery in Île-de-France. On their way there, the commissioner, who turns out to be a Buddhist, Raphaëlle, Astrid and Nicolas discover disturbing elements that question the guilt of the perpetrator of the murder, a drug addict who was prowling in the nearby forest. According to Raphaëlle, the crime was committed inside the monastery.