The operative words here are "sex ring." See if that doesn't bring Parker fans to the cash register. In this case, the ring has two parts. The first is a pair of very wealthy men, each of whom owns a very large yacht aboard which they party with the second part, namely, beautiful young girls with time on their hands and sex, comfort and a cushy life style on their minds.

Which brings ex-LAPD cop--now police chief of Paradise, Mass.--Jesse Stone the case of Florence Plum, a woman who has been thrown overboard by someone at the tiller of a sailboat she rented. A couple of weeks after the murder, her partially decomposed body floats into a cove of Stone's modest seaside village.

It's an inconvenient time given that it's the annual Race Week for sailing vessels. Boat enthusiasts of all description and wealth categories crowd the harbors, docks and streets like just-hatched mosquitoes. Nevertheless, chief Stone gets to work by checking boat-rental places for missing crafts. When he gets the driving license of one Florence Plum of Fort Lauderdale, job #2 is finding out who Ms. Plum was and who she crossed.

From Kelly Cruz, a detective in Fort Lauderdale, Jesse learns that the victim was a recently divorced heiress of the Plum chain of health food markets, and that three yachts in the races are from there. Moreover, the sharp lady cop found a video in Plum's condo, which, when Jesse receives it from her, he duly enters it into evidence and runs it for the squad. It turns out to be a recording of a menage a trois with Florence the centerpiece. The background details give him something tangible to look for aboard suspect yachts in the harbor.

With his deputy Suit, he steps on board Harrison Darnell's Lady Jane out of Miami, looking for a way to tie it in with Florence and, perhaps, her video. After dispelling legal challenges from the owner over a search, he's confronted by a gorgeous blond with challenges of a more personal nature, like enjoying that he's the local yokel police chief. "Maybe I'll call you Jesse," she says. "Or e-mail me," Jesse rejoinders. "Localyokel.com." Despite his insouciant put-off, however, the babe might just be developing a thing for him, even if she's Darnell's preferred squeeze. In this crowd, nothing's sacred, and no one's taken.

When he recognizes a decorative figure and confirms later that it's on the tape, he knows he's tied poor, dead Florence to this particular yacht. But as depraved as steamy sex on a yacht might seem, there's not much the law can do about it and it's no proof of murder. As far as that goes, he again turns to Cruz, who has turned up the entire Plum family--father, mother and twin sisters Corliss and Claudia. The latter are not only known on an intimate basis aboard the Lady Jane but they conceal their recognition of the two guys in the still photos Jesse had made from the video. Something smells fishy.

Sorting it out is Parker's way of reaching into the lower moral latitudes of society--rich guys with a thing for young females and young women with a thing for older men who might also be rich. It's a setting for what some might call depravity, but for more serious crime, the chief has to cast a wider net.

A wrinkle in Stone's love life is the return of his ex-wife, Jenn, a TV news reporter who's just about living with the guy. They're attempting to turn their deep mutual feelings into something more permanent than the first time around. It's nice, but if they didn't discuss, evaluate and weigh it so much, the narrative momentum might flow more smoothly.

As said, author Parker, one of the most successful writers of mystery fiction on the planet, which he pulls off with a seemingly effortless prose style, will have no trouble scoring his usual wide readership with the sheer prurience of his subject. But, alas, for someone who's been reading a share of his abundant bibliography, it grows a bit stale and somewhat strained with every character talking in that clipped, clever, funny way that should, perhaps, be confined to his immediate circle.

This is not one of his best, but it keeps you under the reading light with enough interest to maintain your heading in tail wind of his complex mystery.