SO YOU MAY feel a little let-down when you come to the end of A Body Surrounded by Water (Scribner's, $14.95). Still, there is Charlie Salter, who is an original -- a very human, believable, and likeable guy.

This is the fifth in the first-rate Charlie Salter series from Canadian writer Eric Wright, who has provided some of the brighter moments in the mystery field in the last few years. Unfortunately, a skimpy and patchwork plot mars Wright's latest effort, and it falls short of the high standards of its predecessors. So it's up to Charlie to pull it off. And he almost does, with help from his wife Annie, older son Angus and Prince Edward Island, with its Anne of Green Gables scenery and quirky island characters.

The Salters, with Charlie on vacation from his job as a Toronto police inspector, are spending the summer holiday on Prince Edward Island, where Annie's parents belong to a wealthy and influential family.

Charlie, who grew up in a working-class neighborhood in Toronto, has become more comfortable with his rich in-laws over the years even if they never can be close. He has taken up golf, and it would be a fine vacation were it not for Sheila. A former college classmate of Annie's, Sheila, with the enthusiasm of one having recently entered analysis, feels she has special insight into human relationships, particularly Charlie's with his wife ("deeply dependent on Annie, which sounded bad to him") and Angus ("going through a period of hero-worship of his father when he ought properly to be in rebellion at this stage of his development, leaving Salter wondering what psychological torment he was laying up for his son in the future by playing golf with him now").

Charlie welcomes the chance to get out of the house when the local police ask the help of his expertise in a rare homicide on the island. Clive Elton, the local historian, has been bludgeoned to death, apparently by a burglar surprised by Elton's early return from a trip.

The case becomes more complex when the chief suspect in the robbery-murder is found murdered. In the end, Charlie helps the Mounties get their man. The solution isn't that surprising nor satisfying. You expect more than bungled petty crime in a murder mystery.

If A Body Surrounded by Water is not an unqualified success, yet it has much to recommend it. First, there is Charlie, whom we get to know better with each book. Then there the local color of Prince Edward Island and its insular inhabitants, who do it their way . . .

Three of a Kind

IN A TRIO of new mysteries, women are the central characters as a cop, a private eye and an amateur sleuth.

Jill Smith is a smart, tough-minded homicide detective in Susan Dunlap's police-woman procedurals. She works in Berkeley, Calif., once the hot spot of radical politics, now turning more yuppie than yippie. Today, it seems, Berkeley is becoming as famous for its gourmet restaurants as for its demonstrations of the '60s.

In A Dinner to Die For (St. Martin's, $15.95), a trendy restaurateur dies after sipping his own carrot soup, which has been spiced with a dash of aconite from the horseradish jar. Mitch Biekma's personal flair has made his Paradise restaurant the in spot, with patrons willing to sit on the steps sipping the inevitable white wine waiting for a table.

It's a tough case for Jill, just back from sick leave after suffering injuries in a helicoper crash (in Too Close to the Edge).

First, it's a murder that is getting page one attention from the media. Then her scene-of-the-crime officer is a truculent sergeant who feels he should have been promoted to the homicide slot that went to Jill. And the police have a slew of suspects with good motives and opportunity -- the victim's former college teacher, whose scholarly research has been interrupted by the busy restaurant opened in the neighboring house that she found for him; a volatile woman chef who says she isn't upset that Mitch collected her recipes for a cookbook sold under his name; a college chum waiting to open his own restaurant; a wife who has run the operation while her husband appears on television talk shows, and Earth Man, a holdover from the '60s, who mooches food at the chic restaurant.

Dunlap's police procedurals have the authenticity of telling detail (the average homicide folder is two inches thick with some 150 sheets of paper). In A Dinner To Die For, she adds tasty tidbits on how a gourmet restaurant is operated behind the kitchen. It will satisfy a mystery reader's palate.

Boston is no longer Spenser's exclusive turf. He has been joined by a new breed of Boston gumshoe, including Jeremiah Healy's private eye John Francis Cuddy, William Tapply's attorney-sleuth Brady Coyne, and Linda Barnes' Michael Spraggue.

Now Barnes adds a new name to the growing list -- Carlotta Carlyle, ex-cop, erstwhile cabbie, and now the new private-eye kid on the block. She makes her debut in A Trouble of Fools (St. Martin's, $15.95).

Carlotta could be a winner. She emerges from a tangled plot as a recognizable human being with a distinctive persona. She is red-haired, stands 6 foot 1 inch, wears size 11 shoes (women's sizes seem to stop at 10), plays a wicked game of volleyball, and carries a small can of hair spray as an effective substitute for Mace.

Her tomcat is named T.C. Carlyle, and since Carlotta's phone is in that name, he gets a lot of mail, including credit-card offers and notification that he is a $20,000 sweeptakes winner.

Wouldn't you know that one of Carlotta's first clients would turn out to a little old lady wearing a pair of white gloves?

Margaret Devens hires Carlotta to find her missing brother, a cab-driver who hung out with Irish bar cronies. Things get terribly complicated with IRA sympathizers, drug dealers, a Mafia family, the FBI, the Boston police and sundry others involved. Even T(om) C(at) Carlyle, the sweepstakes winner, gets in the act in the explosive finale at a bus terminal.

Carlotta is an easy-going, breezy narrator. She's sassy but not smart-alecky. She's a Big Sister to 11-year-old Paolina and worries about the wispybearded man loitering around her elementary school. After watching detectives root around the victim's bureau drawers on her first homicide case as a cop, Carlotta goes home and clears out her own closets (letters from her ex-husband, a coupon for breast enlargement cream, a brief attempt at a dairy). Let's hope a new client soon knocks on Carlotta's door.

A blithe-spirited first mystery introduces Amanda Pepper, an English teacher-cum-amateur sleuth. She makes her debut in a novel with a fetching title, Caught Dead in Philadelphia (Scribner's. $16.95), written by Gillian Roberts, the mystery nom-de-plume for Judith Greber, a mainstream novelist.

Amanda comes home to find a body in front of her fireplace. The victim is Liza, a teaching colleague, part-time actress, and fiance'e of a Main Line family scion who is running for state senator. Amanda teams up with an attractive policeman (of course, she thinks he's hostile and unsympathetic at first) to trap the killer.

Amanda has possibilities despite this flawed first outing. The car-drive confrontation in the murderer's Mercedes goes on far too long to hold the suspense. And let's declare a moratorium on mothers who keep calling their unmarried daughters to inquire about their marital prospects.

Re: Morse

THE IRASCIBLE Oxford Inspector Morse returns in British author Colin Dexter's The Secret of Annexe 3 (St. Martin's, $15.95).

The morning after a New Year's Eve costume party at the Haworth Hotel, the first prize winner is found dead, sprawled across his bed in Room 3 in the hotel's still-unfinished annex. It turns out that the victim -- as well as his woman companion and the two other couples staying in the annex-all were registered under false names. So Morse has to sort them out before narrowing his search for a killer.

The Morse series is not for every mystery reader. It is an acquired taste. Dexter never tells a straightforward story. His mysteries, deviously-plotted and multi-layered, are written in an indiosyncratic style with frequent author asides to the reader. Morse himself can be rude, darkly moody, and maddeningly cryptic. It will be interesting to see how he turns out on the PBS Mystery! show this winter.

Jean M. White reviews mysteries for Book World the third Sunday of every month.