Another 87th Precinct procedural from the prolific, proficient McBain--whose penchant for lurid tales of sexual obsession is on display in the central, not-very-satisfying murder mystery. Gorgeous blonde Susan Brauer, 22, is found brutally knifed to death. Then her lover--rich, married, late-middle-aged Arthur Schumacher--is shot down. So: whodunit? Was it Schumacher's wife, his bitter ex-wife, or one of his edgy grown daughters? Meanwhile, in subplots that eventually converge, two black cops search for the druggie youths who robbed and killed the father of series hero Steve Carella; and cop Eileen Burke, trying to rise above her recent traumas (rape, killing a perp), joins the police department's hostage-crisis intervention team. The sex-crazed killer here is unconvincing; the prurient details--in routinely pornographic love-letters--receive more attention than necessary. And there's a tendency toward soap-operatic excess throughout. Still: solidly readable urban policework--with a modicum of authentic tension in two extended hostage-negotiation/rescue sequences.