The overall mood of this police procedural about a serial killer of homeless AIDS sufferers in New York is, astonishingly, upbeat and energetic, even chipper--as befits Mahoney's version of New York as the kind of city where assistant commissioner of the NYPD Brian McKenna (last seen in Edge of the City) can quit his job, take a salary cut, and rejoin the ranks as a detective in the NYPD, all because he loves the work. Here, McKenna is assigned to investigate the demise of a man who apparently froze to death. Prodded by the suspicions of his partner, Maureen Kaplowitz, who is famed for the accuracy of her hunches, McKenna uncovers a pattern of murder. His first surmise is that the killer, who calls himself Hyde in a note sent to the cops, is avenging himself on those who gave him AIDS. But the real motive is as surprising as everything else in this well-written tale--countless times McKenna's initial judgments are proven wrong, usually because he has underestimated everyone from Maureen to Heidi Lane, a sexy young TV reporter who has more on her mind than the news. Even the killer turns out to be more than a maniac out for vengeance. This frequent exceeding of expectations gives Mahoney's tale the high energy of comedy, boosted by sharp, fast-moving dialogue that advances the plot. The result is smart, brisk entertainment.

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, and 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 cliche, 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 the offbeat. Mahoney works overtime piling up impeccably researched detail. The clammy comforts of the squad rooms and precinct offices have never been better rendered.

In a city like New York, where people have perfected the survival skill of closing their eyes and shutting down their feelings, it's tough to work up the public's sympathy for some mean and nasty homeless guy who drinks himself stupid and freezes to death. To most of the population, according to Dan Mahoney in his third novel, Hyde, "stepping over someone lying on the ground is like stepping over a crack in the sidewalk."

Such callousness makes Detective Brian McKenna, the dedicated hero of this city-slick cop thriller, shake his head in dismay. ("Whatever happened to this great city?") He gets everybody's attention quick enough, though, when he spots a homicidal pattern in the deaths of several men infected with the AIDS virus. He then goes and wastes time looking for a vigilante killer bent on avenging himself on whoever gave him AIDS. The killer's real motive turns out to be much more complex; but before the author springs this big shocker, he treats us to some of the finest police work (and the best station house humor) since William Caunitz departed for his final roll call. A retired police captain, Mr. Mahoney goes through the procedural paces--from interviewing hostile witnesses to goading the lab boys to do a fingerprint analysis--with terrific energy and know-how. Brian McKenna knows how New Yorkers live and die. Dan Mahoney knows how they work.

NYPD Brian McKenna is back where he loves to be, working the streets as a detective. Brian, along with his partner, Maureen Kaplowitz, investigate the death of a homeless person. At first, it appears that the victim is just another one of the city's helpless, who happened to freeze to death in the bitter winter. However, based on Maureen's uncanny instincts, she and Brian notice a pattern in this death that matches recent similar ones of other homeless people, all infected with the AIDS virus.

Brian concludes that Hyde, an individual who has informed police that he plans to off AIDS patients, is the culprit. Brian knows that he must quickly uncover the identity of the serial killer before more people die in Hyde's seemingly complex acts of vengeance.

Hyde is an excellent mixing of a serial killer who-done-it with a police procedural that brings alive the mean streets of New York City. However, what makes Dan Mahoney's novel appear to be above most of the sub-genre is the author's uncanny ability to surface social issues such as AIDS and the homeless without being a liberal preacher. This novel and the two previous McKenna novels (Detective First Grade and Edge of the City) are all worth reading for their feel of the city that never sleeps.

"Seek `Hyde' if you enjoy killer thrillers"

Brian McKenna has had it with being an assistant commissioner and is reporting for duty as a detective first grade with the 17th Precinct as Dan Mahoney's new novel, "Hyde," opens.

Brian is much happier as a detective than he had been as a paper pusher, and it doesn't take long for him to be assigned to his first case--a homeless man who apparently froze to death. But to Maureen Kaplowitz, the detective taking the call with him, it looks like murder. And murder it is.

The killer is targeting homeless men infected with HIV, sharing his poison-laced wine with his targets--and only his targets. This killer is not indiscriminate; he has a carefully compiled list and a devastating rationale for his choices.

This is a "don't miss," for Hyde is well-written, as well as being expertly and meticulously plotted. Fortunately for new Mahoney fans the novel will generate, the author has two earlier novels, Detective First Grade and Edge of the City, available in paperback.