In 1380, the King's parliament debates whether to grant money supplies to the Regent John of Gaunt for his war against the French. John orders Cranston to investigate the murders of the Shrewsbury representatives; the assassin must be caught before parliament suspects the Regent. Both Cranston and Brother Athelstan have their own problems: the coroner is puzzled by a thief stealing cats from Cheapside; Athelstan is concerned by claims that a devil is prowling his parish. Against the colourful pageantry of medieval court life and the dark slums of London, Cranston and Brother Athelstan pit their wits against a bloody murderer and the assassin in the House of Crows.