Doherty, author of a lively historical-crime reconstruction (The Death of a King, 1986), goes even further back in English history--to the reign of Edward I, circa 1284 A.D.--to begin a mystery series featuring Hugh Corbett, clerk in the Courts of King's Bench. In this so-so debut outing, Corbett is asked to investigate the ""suicide"" of goldsmith Lawrence Duket--which the King's top adviser believes to be connected to the treasonous doings of a secret London ""coven"" (following in the radical/Satanist footsteps of Simon de Montfort). Indeed, Corbett soon finds evidence that Duket's hanging at the church of St. Mary Le Bow was murder, not suicide. And just before being killed, it seems, Duket himself assassinated shadowy moneylender Crepyn, a villain with links to the coven. So Corbett endeavors to find out exactly how Duket died, and who the coven's leaders are--while falling hard for Crepyn's reputed mistress, beautiful innkeeper Alice. The trail leads to a male brothel, to near-fatal scuffles by the foggy Thames, to the Tower of London. But the unmaskings of the coven-mastermind and the spy in Chancery are totally unsurprising. And while 13th-century London is made sporadically vivid, with a few grisly sideshows, the stagy dialogue lacks period conviction and the characters remain one-dimensional. Still, if a cut below Ellis Peters and Leonard Tourney in the crucial areas of plotting, personalitY, and atmosphere, this is a sturdy addition to the English-historical-mystery shelf--with promise, perhaps, of richer adventures to come.