When a corpse clutching a crystal chess piece is found in the old fortress of Bitche, in the Lorraine region, police lieutenant Nicolas Muller is sent to investigate. He is accompanied by a young female intern and soon discovers, during this complex investigation, that he is actually related to her. While the Lorraine is familiar ground to Muller, being his birthplace, his investigation is made difficult by the fact that all the clues point to a crystal factory managed by his own father and sister - a family legacy he turned his back on by becoming a policeman. The number of victims soon grows, as does the list of suspects, among which are his own family members.—Happy_Evil_Dude

When a corpse clutching a crystal chess piece is found in the old fortress of Bitche, in Lorraine, lieutenant Nicolas Muller is sent to investigate, accompanied by a young female intern and soon discovers that he is actually related to her.—Happy_Evil_Dude

A burned corpse of a woman is discovered inside the Bitche citadel, in Lorraine, carrying a crystal chess piece. Lieutenant Nicolas Muller investigates with his gendarme warrant officer Patrick Joly and a new recruit intern Lola Paoli. This crystal factory belongs to his father Hervé Muller. The victim is identified as a factory worker. Soon two other factory workers are killed on a broken neck. Muller learns from his younger sister Florence Muller that in order to prevent the crystal factory's bankruptcy, she intentionally set fire to the factory with the purpose of collecting insurance money, but unaware of the first victim inside. Further, Muller finds out that Patrick Joly is the killer of the second and the third victim. As the first victim's boyfriend, he took revenge on them since they are the fire-setting helper of Florence Muller.