Seventysomething historian Sister Mary Teresa Dempsey, head of Chicago's three-person remnant of the Holy Order of Martha and Mary, is as sharp as ever here (Sister Hood, etc.) and still capable of being upset by the waywardness of former students. One such is Margaret Nelson--wife of book dealer and restorer Gregory Doyle and mother of three grown children--who has divorced her gentle husband and is seeking adventure. The wrong kind seems to have found her when daughter Bernadette discovers her bludgeoned body in the house Margaret retained after the divorce. Sister Mary Teresa keeps a low profile through all of this, even through Gregory Doyle's patently false confession, until a second killing- -that of volatile antiquarian Professor Joseph Kotarski--prompts her to devise an elaborate trap for the out-of-left-field killer. One of the better efforts in this series from Quill (aka Ralph McInerny): cluttered and uncompelling but comfortable diversion.