It's 1302, and Sir Hugh Corbett (The Assassin in the Greenwood, 1993, etc.), chief clerk to King Edward I, is once again on a mission for his sovereignthis time dispatched to Sir Simon Gurney's Mortlake Manor in Norfolk to investigate a pair of macabre murders. Also present at the Manor is Lavinius Monck, right-hand man to the Earl of Surrey, whose business here has been kept secret from Corbett but whose young clerk Cerdic was found, beheaded, on the tide-ravaged shore. This was followed soon after by the death of the local baker's wife, Ameliaher body found hanging from a crude scaffold. A religious sect called the Pastoureaux, housed nearby in the Hermitage, is a source of concern, especially after Marina, one of its young converts, is discovered on the moors, raped and strangled. Corbett, stalwart aide Ranulf ever at his side, presses his inquiries in the nearby village, at the Hermitage, and at the richly appointed priory, questioning local cleric Father Augustine and physician Selditch, among others. It's soon apparent that much, though far from all, of the present villainy has roots in the pastspecifically in the ill-fated expedition of King John in 1216, in which a huge convoy of treasure was supposedly lost in the treacherous Norfolk bogland known as the Wash. Too many kinds of mayhem are at work here, and the story loses focus as crimes, old and new, proliferate. The neatly contrived denouement helps save the day, but this is middling Dohertybest enjoyed by devotees of the medieval mystery.