Roberta Gellis, . . Forge, $25.95 (432pp) ISBN 978-0-7653-0019-5

Once again, Gellis proves herself a master of the medieval historical in her third outing (after 2001's A Personal Devil) to feature whorehouse mistress Magdalene la Batarde. In June 1139, Magdalene's patron, William of Ypres, calls her to Oxford, where King Stephen is holding his great council. Her reservations that something may be amiss are confirmed when the detestable Aimery St. Cyr is stabbed to death, and one of Sir William's men, Niall Arvagh of Murcot, is the prime suspect. Ensconced at her old whorehouse, the Soft Nest, Magdalene joins forces with Sir Bellamy of Itchen to find the murderer before there's a political scandal. The plot is as skillfully woven and as intricate as a medieval tapestry, though the large number of characters means the action plods at times. (The author's note at the end does much to clarify the many historical personages involved.) Meticulous attention to detail, from the takeout of cookshop food to the mail shirts men wore, and believable human characters, notably the intelligent, courageous, caring and compassionate Magdalene, help put Gellis at the forefront of this popular mystery subgenre. (Dec. 4)

FYI:Gellis has won a Romance Writers Association's Lifetime Achievement Award.