Solange Dorval is found murdered in front of the Basilica of St. Nazaire in Carcassonne, one of her hands severed. The surveillance cameras show that the killer was wearing a cloak bearing the cross of the Knights Templar. For Police Captain Angélique Demange, who must reluctantly team up with her ex-husband, it is the beginning of a thrilling case that may lead them to the treasure of Rennes-le-Château...