McBain's 45th novel of the 87th Precinct--and you can see that practice has made this latest not perfect but perfectly easy to enjoy, with--per the formula--several parallel plots, fueled not by their modest inventiveness but by the author's confident prose: McBain knows these cops and their city of Isola like Satan knows sin, and it shows. Even the chief villain is familiar: the Deaf Man, resurrected from Eight Black Horses (1985), etc., and up to his old trick of laying tantalizing clues to a big crime--here, excerpts from a scholarly work on crowd behavior mailed to arch-nemesis cop Steve Carella as the Deaf Man plans unspecified mayhem connected to an upcoming free outdoor rap concert. (In addition to tracing the Deaf Man's elaborate planning--including tinkering with the concert's sound system and stealing a garbage truck--McBain follows one rap group's prep for the concert, which flowers into a touching romance between a singer and a composer's widow.) Also on the precinct's plate is a series of murders of graffiti artists--with one of the victims being not the expected inner-city rebel but the respected attorney in whose closet the cops find a stash of spray-paint cans. And then there's the rash of ``dumpings'' around Isola of Alzheimer's sufferers, with all identifying tags ripped from their clothing. Several subplots--a hostage crisis; a clash of pro-lifers and pro-choicers that sees Carella's deaf-mute wife drenched in blood--add further gritty big-city texture, and McBain closes out the three major cases in clever, though not inspired, fashion: most gripping is the aftermath of the Deaf Man's big caper, a noir-style fadeout in a hot-sheets motel. Not up to the series' best but still steadily engrossing cop- fare from an old hand.