Estevar Borros, one of the legendary sword-fighting magistrates known as the Greatcoats and the king's personal investigator of the supernatural, is no stranger to tales of ghosts and demons. When the fractious monks of the abbey rumoured to be the birthplace of the gods begin warring over claims of a new pantheon arising, the frantic abbot summons him to settle the dispute. But Estevar has his own problems: a near-fatal sword wound from his last judicial duel, a sworn knight who claims he has proof the monks are consorting with demons, a diabolical inquisitor with no love for the Greatcoats, and a mysterious young woman claiming to be Estevar's ally but who may well be his deadliest enemy. Armed only with his famed investigative talents, his faltering skill with a blade and Imperious, his ornery mule, Estevar must root out the source of the madness lurking inside the once-sacred walls of Isola Sombra before its chaos spreads to the country he's sworn to protect.