At the opening of an exhibition on the Inquisition in a famous Cathar castle, the first visitors are shocked to discover the mutilated corpse of a young woman in a torture cage. Victor, a young man with Down's syndrome, is found at the scene of the crime and is the main suspect in the case. He never stops claiming his guilt for the murder. Pauline Lebrun, a lieutenant in the gendarmerie and the suspect's sister, is immediately removed from the investigation. Convinced of her innocence, she is replaced by the captain of the Montpellier Regional Police, Thomas Costella. From then on, she will never stop fighting to protect her brother and get the truth out. But trying to prove her brother's innocence at all costs will not be without consequences.
—Happy_Evil_Dude