It's growing dark, and a cold May nor'wester riles the gray Tred Avon as the last ferry leaves Oxford for the less tony environs of the river's far bank.

On the crossing, I squint at scribbled directions to Oysterback, the town with "characters we haven't even used yet." Its annual Mosquito Festival is an international beacon to aficionados of Culex pipiens. Oysterback is a fiction, of course. It exists nowhere -- also somewhere every day, on Maryland's Eastern Shore. Mostly it exists in the fertile brain of Helen Chappell -- "last house on the right, past the general store, the one with peeling paint," she said.

Chappell, 47, has conjured Oysterback and its denizens for five years on the Op-Ed page of The Sun. Now she's collected her dispatches in the delightful "Oysterback Tales" (Johns Hopkins Press).

You ought to visit. Down at the Blue Crab Tavern, proprietor (and major Elvis fan) Desiree Grinch tells it as she sees it and serves both the living and the dead. You might be lucky enough to see the Jell-O Mold-Off contest at the community center, won usually by Miss Nettie Leery. Who could resist her Harlequin Pecan Cool Whip Fantasy?

Maybe you'll be passed by Huddie Swann and Junior Redmond in their motorized duck blind; or catch "Teenage Girls in the Old Testament," performed by the students at Patti's Christian School of Tap and Ballet.

Your laughter might grow quiet, listening to Johnny Ray Insley recall "the floater," the young waterman who drowned; how it's ++ the little things you remember years later -- the crab that dropped off his finger, ambled across the deck and dropped into the bilge with a little splash.

Singly, any of the "Oysterback Tales" is a good, if brief read. But it's the way they build in the book, sketch upon sketch, into a full-fledged community that is the genius of what Chappell does. "I wanted it to be funny, but I wanted it to be a place where everybody cares about each other -- where I would like to live," the author says. "The characters aren't fools . . . and the humor is never meant to hurt."

Perhaps it's what the author doesn't tell you about her creations, or only hints at, that makes Oysterback so compelling. We can only wonder how Ferrus T. Bucket, world's oldest waterman and antique decoy counterfeiter to the yuppie tourist trade, learned to speak -- and dream -- in "perfect Parisian French."

There's no doubt we've only begun to plumb the depths of Hudson Swann, a Vietnam veteran and tonger who has communed with mermaids while oystering. Nor could Desiree Grinch have developed her worldview in Oysterback alone. Then there are the recently reappeared Boone brothers of the Uranusville marsh, who dropped out of even Oysterback's mainstream in 1969. Expect odd doings from the Boone brothers in future installments.

One wants to know how much of Oysterback is sprung from Chappell's own past. She, like her characters, is an original. Over dinner she laments her recent falling out with The Prince of Tilghman Island, as she called a real-life waterman she appropriated for an Oysterback tale. "He says I'm too damn nosy. I told him he's banned from the Blue Crab for two weeks."

Perhaps the Prince had a point. As you pick up the check, Chappell grabs your wallet and begins inspecting the contents. "I love to look through people's wallets. Oh, here," she says, offering hers in return.

If you were locating Oysterback in space and time, Chappell says, you could start with Tilghman Island, spice it with Hoopers Island and stir in the Tyaskin-Bivalve-Wetipquin area of western Wicomico County -- "everything from Dave's Sports shop south on Route 349," she says.

Then you'd have to go back to the 1950s and 1960s, to a childhood gloriously spent, prowling the "neck" country west of Cambridge: great peninsulas of marsh and field and forest, incised deeply as a white oak leaf by tidal creeks of the Choptank and Little Choptank rivers. Her father, a surgeon, owned an 1,800-acre farm with some five miles of shoreline there. Best of all, she recalls, was John Lewis' store in nearby Hudson -- still there.

"That was an inspiration," she says, "listening to all the old watermen and farmers sit on the long benches and tell stories." It was a "bad move" when her father sold the farm for a place in Oxford, when she was 18.

Nothing in her life seemed to point to Oysterback through the decade of the 1970s. It was Boston, New York, struggling to write, clerking at Macy's, living in Soho with a painter. Writing included three novelizations of scripts from "Policewoman," a television series starring Angie Dickinson; also the first of more than 20 Regency Romances, paperbacks on early 19th century England under the name Rebecca Baldwin.

In 1981, her father died. She says: "I had a little money and moved to Talbot County to finish a novel. It was a very dark work, about the end of an era, the end of a culture. It was called Oysterback, which in the novel was the place Hudson Swann went to be depressed.

"I would finish the novel in a year and move back to New York, rich and famous. I really believed that. After five different editors, it just died on the vine, and I went back to Regency Romances to pay the rent."

Far too much of the 1980s, Chappell says, she can sum up as "deaths . . . rotten love life, career dead . . . recession, depression." She says she kept a sign on the wall that warned: "I've got PMS and a handgun."

Oysterback (the happier version) took form in 1989 after a bad reaction to Prozac hospitalized her. At a friend's suggestion she began exploring ideas for an occasional Eastern Shore article with Hal Piper, Op-ed page editor of The Sun.

One day, "out of the blue, it just came to me, the idea for a piece that parodied a small town newspaper (she had worked as reporter and editor for the Cambridge Banner's Easton edition). So was born the Oysterback Bugeye, whose editor, Helga Wallop, is also an artist, her work displayed as far away as the First Bank of Delaware.

Now that "Oysterback Tales" is out and selling well, Chappell is on a bit of a roll -- though a paying job would be better, she says ruefully. She's completed Oysterback, the play, which ran last month to sellout audiences for seven nights in Churchville. It will be presented again on July 2 and July 3 at Easton's Avalon Theatre.

And she's finishing the manuscript for "Ghost of a Chance," which she hopes will be the first in a mystery series. It stars Hollis Ball, a hard-bitten reporter, and revolves around wetlands development and the Greenhead Army, a band of eco-warriors who strike polluters from deep in the Dorchester County marsh.

As for Oysterback, it lives monthly in The Sun.