It's 1303 and Edward, King of England, has asked his onetime courier and chief clerk Sir Hugh Corbett (Satan's Fire, 1996, etc.) for help with a series of disasters besetting the town of Oxford. The university's Sparrow Hall, founded by the late Sir Henry Braose and his sister Mathilda, has been the scene of several faculty murders--Regent Copsale; much-loved librarian Ascham; and his friend Passerel, found poisoned in a local church. Then there are the headless corpses, mostly of beggars, found in the woods outside town. Compounding it all are the proclamations, signed ``Bellman,'' nailed to church doors and elsewhere, that praise the glories of the King's dead enemy the Earl de Montfort. Sir Hugh reluctantly agrees to investigate and, with faithful servants Ranulf and Maltote, moves into Sparrow Hall, where Mathilda still resides with her deaf-mute servant Master Moth. The students are an unruly lot, largely Welsh, bearing no love for the King and given to debauchery, and possibly worse, in Oxford's woody outskirts. Meantime, the masters have their own secrets, and more of them will die before Sir Hugh unmasks the evil spirit behind the mayhem. Tenth in a series that grows denser and more convoluted with every episode. Tension ebbs and flows sporadically amid the churchly rites, rehashed battles, hooded figures ever lurking in dark corners, and repetitious accounts of the town's filthy lanes and seedy inhabitants. A tangled, torpid slog.