The charred body of a man is found in the forest of Brocéliande by a little girl. Éric Jourdain and Marie Delorme, a couple on the verge of breaking up, are in charge of the investigation. The little girl explains to the gendarmes that a boy showed her the body. The boy is found in shock, unable to speak. He draws though. His drawings resemble local legends linked to the myth of Merlin the Magician. Marie's brother, Romain, a child psychiatrist comes to the aid of the gendarmerie. Who is the victim ? Who is the boy ? Is it related to the murder?