This slam-bang addition to former NYPD Captain Mahoney's superior police procedural series about detective Brian McKenna (Edge of the City, 1995, etc.) is the third, and by far the best, of the lot. After turning down a job as assistant police commissioner, McKenna voluntarily downsizes himself back to the detective division, putting on his old First Grade badge at the tony 17th Precinct in midtown Manhattan, where his partner, the brassy, 59- year-old Detective Maureen Kaplowitz, can still show him a thing or two--and the older, wiser, slightly mellowed McKenna is eager to learn. No longer quite the hard-charging maverick we met in Detective First Grade (1993), McKenna cleverly uses his knowledge of police bureaucracy to his advantage after he notices that the death of an AIDS-afflicted homeless man--seemingly frozen to death on a frigid night--bears a disquieting similarity to other deaths among Manhattan's street people. It seems that a gaunt character in a dark hat, known as Dracula, is slipping poisoned wine to homeless and HIV-positive men. McKenna and Kaplowitz make speedy progress in pursuing the one who might be New York's first nonviolent serial killer when the tritely ambitious TV news reporter Heidi Lane decides that the cops aren't working fast enough and singles out McKenna for on-the-air goading and abuse. While Lane is something of a genre clichÇ, and the villain, who calls himself ``Hyde'' (a Nabokovian physician who collects butterflies), is an old turn on the sophisticated debauchee, Mahoney's peerlessly rendered cops, bureaucratic deadbeats, and only-in-New-York types (a sly, no- nonsense bank manager is named--no kidding--Charity Bucks) display his seasoned eye for the eccentric and offbeat. Mahoney works overtime piling up impeccably researched detail. A rousing improvement over Mahney's earlier efforts yields a coolly understated police procedural. The clammy comforts of squad rooms and precinct offices have never been better rendered.