It's the summer of 1380 and the corpse of Edwin Chapler, clerk of the Office of the Green Wax of the Chancery, has been pulled from the Thames: Chapler has drowned, but not before he received a vicious blow to the back of the head. Then Bartholomew Drayton, a usurer and money-lender, is found dead in his strongroom, a crossbow firmly embedded in his chest: a real mystery because the windowless strongroom was locked and barred from the inside. So who killed him; And how; And are the two deaths connected; Sir John Cranston, the Coroner of the City of London, comes to survey the scene. When other clerks are murdered, each with a riddle pinned to his corpse, Cranston enlists the help of his secretarius, Brother Athelstan; and together they must pit their wits against a deadly adversary bent on murder and mayhem.