Barry Trupin, the most talked-about newcomer to the Hamptons, whose battle over the future of his $25 million castle by the sea became the cause ce'le bre of the summer of '84, threw a cozy dinner party for a few close friends here a few weeks ago.

It was no barbecue on the deck.

When the Trupins entertain -- as when they build a house -- they seemingly know no bounds. So on a sultry Saturday night, in their smaller 50-room mansion down the road from Dragon's Head -- temporary quarters as the castle is constructed -- Barry and Rene'e Trupin brought back the 14th century.

While village elders hissed over the excesses of these arrivistes, guests chez Trupin gorged on a 13-course medieval feast complete with a roasted boar, an apple between its teeth. Tapestries celebrating heroic battles and banners emblazoned with family crests hung from the ceiling. Suits of armor were stationed around the living room, and two 10-foot stuffed bears peered out through leaded glass windows at the inky Atlantic Ocean.

Trupin, 48, a self-described poor boy from Brooklyn who says his fortune in computer tax shelters has mushroomed to more than $300 million in less than 10 years, admitted that the idea for the fete came from the 1939 movie "Tower of London." In the film, a character based on Richard III kills his adversaries to get to the throne.

"He was poisoning everyone in his family," Trupin said mischievously. "So I guess we'll have to watch what we eat."

Four years under construction, three years from completion, no expense spared on materials or design, Dragon's Head rises defiantly from the dunes in this land of make-believe, a cinderblock fortress, the raw outline of the Loire Valley chateau the Trupins have dreamed of -- far more house than mere facts can convey.

If it is ever finished, the largest private house in the history of the state will be a fantasy come to life. Guests will frolic under a 30-foot waterfall cascading into an indoor saltwater swimming pool, well-stocked with tropical fish. They will recline on Turkish pillows in Muhammad's Alley or fill their cups in the Normandy Pub, two of the castle's 63 rooms. No interlopers will dare storm the ramparts -- if the chimeras, gargoyles and griffins don't scare them off, the armed guard will.

But given the outcry over this gothic spectacle, Dragon's Head might as well spit flames and smoke. After a yearlong battle led by a small band of vigilant summer residents, all work on Chateau Trupin ground to a halt last May and will not resume until a settlement is reached between Trupin and the village over the building code. Negotiations have dragged on all summer. Meanwhile, claiming that he has been denied his constitutional rights, Trupin has sued the village for $4.5 million in personal damages.

The design of Dragon's Head is not what upsets the mostly rich second-home owners in the Southampton Association, one of whom warmly pointed out that the house reminded him of Malcolm Forbes' chateau in Normandy. Far more outrageous -- and less traditional -- structures have sprung from these beachside fields where potatoes once grew.

What seems to bother the neighbors is Trupin himself. Somehow, he has nearly completed his dreamhouse without a building permit -- and, horror of horrors, has already exceeded the local height limit. But why the village continues to do costly battle with the parvenu has less to do with a few 65-foot turrets than with what many fear Trupin represents.

"You know Trupin has installed slot machines in the basement of Ocean Castle," says Charlotte McDonnell Harris, the self-appointed leader of the anti-Trupin campaign. "I mean, what more do you need?"

"This is embarrassing," says Trupin. He says the one-armed bandits are for the amusement of his guests. "They call it 'The Trupin Affair.' They call me names. They take out ads against me. There are no civil liberties for the rich -- I'll make my own civil liberties."

Barry Trupin cannot believe this is happening to him. Until he hired Howard Rubenstein, a New York public relations agent whose clients include Australian publisher Rupert Murdoch, he had no idea what to say to the reporters who hounded him day and night for his story. Then an article in New York magazine implied that Charlotte Harris doesn't want him in the Hamptons because he is Jewish.

"I'm just a poor Jewish boy from Brooklyn," says Trupin. "I mean, this is 2,000 years of persecution. I cannot believe it."

"I thought he was Italian," snaps Harris. "I didn't say, 'We don't want him, he's Jewish.' Carol Petrie the wife of retail magnate Milton , Ginny Salomon wife of Robert, of Salomon Brothers brokerage house are good friends of mine. No one says we don't want Jews out here. That reporter misquoted me." Marie Brenner, the reporter, did not return phone calls.

Harris, who once dated John F. Kennedy and whose mother, she says, quipped to the late president, "I am glad you didn't marry her," is the publisher of the curmudgeonly Tradition Party Journal, a local newsletter. A husky-voiced blond whose Irish Catholic Murray-McDonnell family led the social set during the Depression, she has led her campaign to raise the village drawbridge for more than two years.

But Trupin had already crossed that metaphoric bridge. In fact, life in Southampton started out quietly for Barry and Rene'e, a couple of new-to-money newlyweds, both for the second time, driving out to the beach in their 1932 Rolls-Royce to find a summer place. Like others who arrived in the late '70s, the Trupins had heard and read about Southampton but had never been invited. "I thought the Hamptons were for secretaries," says Barry. "I had always dreamt of living out here," Rene'e, who once worked as a secretary, says with a sigh.

Though the Trupins didn't fit in among the Old Guard villagers in pink pants and deck shoes, at first no one noticed. Barry, who tends toward gold neck chains, and Rene'e, in her black leather mini-skirt, were members of a new wave of Hamptons arrivistes, part of the trickle-down crowd that has flowed into the beach towns 90 miles east of Manhattan with crisp new dollars.

Real estate has always been expensive out here, but in 1979 it was still possible to buy one of the famous beachfront mansions -- once coyly called cottages -- for under $1 million. First the Trupins looked in Westhampton Beach. Its swinging singles scene and mayor who recently won on the Fun ticket, however, only confirmed Barry's original impression. Then they discovered Southampton, with its sheared privet hedges and rambling, Gatsby-esque houses, its Gin Lane and outposts of Elizabeth Arden and Lily Pulitzer, its Gloria Vanderbilt and Princess Lee Radziwill. They plunked down $700,000 for the old Georgian place that Henry Francis du Pont had built in 1923, the biggest house in a village of big houses.

At first Rene'e thought she would just spruce up the decaying mansion, "throw up some chintz curtains and redo the bathrooms." In 1980 Rothschild Reserve International Real Estate, one of Trupin's many corporations under the name he borrowed from the French banking family, made its first application for a building permit. The village granted the firm a permit to spend $15,000 remodeling the kitchen.

The Trupins then made their first mistake. The plumbing was shot, so they called in Wines and Sons to redo it. Roy Wines is the mayor of Southampton. In fact, since the summer people generally vote in New York City or wherever home might be, the town tends to be run by the local tradesmen, who have the majority of the vote. Little could the Trupins have known, they say, that Wines is a very unpopular pro-development figure in the eyes of the Southampton Association of summer people and "gents" -- and, most notably, Charlotte Harris. "Roy Wines is a wimp," she has declared more than once.

Business was good for Trupin in the early 1980s. Very good. He says he had little time to concern himself with village politics. His Rothschild Reserve International, which the retreaded nuclear physicist founded in 1977 with a couple See TRUPINS, G7, Col. 1 TRUPINS, From G6 hundred dollars, had cashed in on the lucrative computer tax-shelter business. The income from lease-backs and other forms of complex investment was pouring in -- why not flaunt it?

So in the fall of 1981 Trupin decided to build a chateau on top of the old du Pont place. He hired John Olson, a contractor with years of experience in erecting hotels and restaurants quickly. The steel framing went up, and by 1982 the work began to look like far more than a spruce job, yet still no one noticed. "We thought some Rothschilds fleeing France were fixing up the old place," says Harris. "After all, we've gotten a lot of those Euro types out here recently."

Like others who have money, the Trupins went to Europe and shopped -- with a vengeance. They picked up a pair of neoclassical marble mantelpieces from the old Rothschild Piccadilly town house in London, a set of concrete chimeras for the garden. Bidding by phone, Trupin paid $3.2 million for a suit of armor from Hever Castle at a Sotheby's sale across the Atlantic in London.

Work on Dragon's Head proceeded apace -- with stonecutters imported from Vermont, Carrara marble from Italy, $100,000 in plywood from Southampton Lumber Co. -- and suddenly the village began to sense that something big was happening out on Dune Road.

Early in 1983 Southampton building inspector Eugene Romano started writing letters to Olson, directing the contractor to apply for a building permit. Olson didn't respond at first. But then Trupin replied, pointing out that his project was putting millions of dollars into the village, and that he wasn't ready to apply for a permit. He didn't mention that more than $300,000 of those millions had been spent at Wines and Sons, but Romano already knew that. Roy Wines is his boss.

"I suppose you might say we got ahead of ourselves," says Trupin. Most people who build new houses find that changes occur during construction. Trupin had his architect, Darius Toraby, change the plans again and again -- a wing here, a turret there, raise this roof line, open up that central hallway. "I thought about the house every night before I went to bed," Trupin says. "I wanted to make sure it was perfect. And for this perfection they are telling me I have to cut off my turrets?"

If Harris had known about "The Trupin Affair" when she ran for a seat on the village board of trustees, she might have won the June 1983 election. But she soon made up for lost time, and by the end of last summer had become the Trupins' chief nemesis.

One day she drove out to Dune Road, pointing her red Cougar and its chrome Welsh corgi hood ornament toward the narrow beachfront strip on the outskirts of the village. She marched up to Ocean Castle, hoping to get a close look at this "cute, hip number," as she calls Rene'e, with a petition in hand to stop the town from assessing property owners along the beach road for repairs. "I am a very big property owner out here, and I have no intention of paying for the repairs," Rene'e told Harris as she brusquely shut the door.

"Imagine!" exclaims Harris, perched on a bamboo settee in her chintz-filled sunroom, next to a needlepoint pillow proclaiming "God Made the Irish #1."

Harris brought the Trupin matter up at every possible village meeting. She wrote fiery letters to the editor of the Southampton Press. She took out an ad in the local paper: "The Law Is Being Broken in Our Town." While many of her friends returned to New York in the winter, Harris remained out at the beach in the trim colonial house she says "could float in Mr. Trupin's aquarium" and fought for the "good of the village." She even tried to interest "60 Minutes" in what she calls "our Watergate."

Last winter the Trupins were rounding Granada in their 150-foot yacht when the bad news finally hit home. "How to Ruin the Hamptons" ran a headline in W over a picture of the bare-bones Dragon's Head. "Turrets Called the Height of Hideosity" ran a headline in Long Island's Newsday. Then Roy Radin was murdered in Los Angeles. Radin, who has been linked with drug runners and the Mob, had sold Trupin his Ocean Castle, the house a few driveways down from Dragon's Head. "The Whale can find no connection between Radin and Trupin except the property transaction," stated an editorial in The Southampton Whale.

No telling what it would have printed if it had known that Radin tried to call Trupin the night before he was murdered. "He probably needed money," Trupin says. But Harris and her ilk had all they needed.

"Our biggest fear," says one member of the Southampton Association, "is that Southampton will turn into Atlantic City."

"Why let the truth get in the way of a good story?" one of the more philosophical summer residents asks glibly.

Then Trupin discovered that Harris had built onto her Zero Squabble Lane house without a building permit. "It's really apples and oranges," says Harris. "We didn't throw up 65-foot turrets. My house used to be what's called a 'ranch' in real estate parlance -- I mean, real cheesy. We added a second floor and turned it into a 'cape.' I thought the contractor would take care of the building permit."

"So did I," Trupin retorts.

Harris's permit was granted after the fact and long ago. Trupin has applied for a number of permits, which have yet to be granted.

Charlotte Harris is right about at least one thing: Southampton has changed in the past four years. Condos have sprung up in the village, much to the dismay of traditionalists. A string of frivolous boutiques lining Jobs Lane and Main Street attracts throngs of day-trippers from less tony parts of Long Island. But move away from the crowds, with their ice cream cones and saltwater taffy, and suddenly a genteel world of swans and croquet comes to life, an insular world of blonds in kelly green and pink, the perhaps apocryphal setting of F. Scott Fitzgerald's "The Great Gatsby." Beyond the virtually unchanged estate section, where the houses have names and the servants still use the back doors, the neat rows of linden trees and acres of lush green lawns give way to scruffy beach grass and sand dunes, from which Dragon's Head rises.

Barry Trupin is dressed in white trousers, green knit jersey and Roman sandals. His troublesomely curly brown hair is blown into wings by the salty wind. He is a short man, a dwarf next to his turreted Xanadu. There he stands, the landowner and castle-builder, the owner of a fleet of seven Rolls-Royces, glaring at the endless line of motorists who slow down to gawk at his dreamhouse, reassuring one of the armed guards that a visitor may pass and suggesting that the only way to get the whole house into one picture is to walk across Dune Road and over the marshes on a wooden bridge to his dock on the Shinnecock Bay.

"Don't stand there!" he yells at the photographer. "No, no, no, the house looks huge from there." The mansion next door, which is 3 1/2 stories tall, looks like a doll's house next to Dragon's Head.

Joined by Rene'e, Trupin leads the party through the giant portal, across a football field of unfinished construction and crates of tchachkas from around the world, and into TIME, the Trupin Indoor Marine Environment, the "aquarium" Charlotte Harris said her house could float in. And it could. A replica of the Great Barrier Reef, complete with jagged rocks from some faraway ocean bed and underwater grottoes, the aquarium is the main event in this house of many wonders. Once completed, banyan trees brought up from Florida will shade the glassed-in room, and the warm saltwater pool will be filled with tropical fish -- parrotfish, angelfish, groupers.

"No, we are not putting live sharks in the pool," Rene'e says. She is rigged out in an all-white disco outfit -- tight pants, turned-down ankle-high boots, silvery coiled headband. "I don't know who starts these rumors. What we wanted was a school of dolphins, but it is against the law to keep dolphins. So we'll settle for angelfish."

The party, joined by Mike Capelluzzo, the marine biologist in charge of TIME, moves out of the aquarium, up a spiral staircase cut into rough rock, to the glass-walled master bedroom area. The talk turns to the lawsuit. Trupin directs everyone's attention to the conical ceiling rising above the room. "This is what the village wants us to cut off," he says. "About half the turret would go."

Trupin has hired a surveyor to measure the height of other houses in the neighborhood. None is as high as his, but some are higher than the 35-foot limit. "We've given them stacks of plans, which they refuse to look at. We've pointed out that it would cost a cool million to tear down the turrets. But they want me to put even more money into the village. They do all sorts of things out here -- build up the front of the house with sand to disguise the height. But they single me out."

"We could do that here," Capelluzzo offers.

"That would be just game-playing," snaps Rene'e. "Why must we have to go through all this? It's costly. It's aggravating. It's foolishness."

Down another flight of stairs, past the hand-carved jade fireplace from Bolton Castle in Scotland, across the Great Hall, which will be sheathed in Carrara marble and lined with flowering orange and hibiscus trees once the project is finished, the group tucks into the Normandy Pub. It's a small and cozy room, furnished with an antique croissant stove from France, brass and bronze fixtures topped by griffins and gargoyles, walls finished in white stucco and raw beams.

"Here's the crime," says Trupin, guiding all eyes around the room with a wave of his hand. "Look at these beams. Perfect. I distressed them myself with a chainsaw and blowtorch. Look at these bronze hinges. My father made these with his own two hands. Here's the crime -- that someone should want to come here and do something perfectly."

"Let me show you the room everyone got upset over," Trupin says, leading the tour past the old du Pont dining room, past the spot where an elaborate hand-carved glass mermaid with real coral hair will one day hang. He stands in his Muhammad's Alley. "I wanted it to be like an Arabian fantasy. With Turkish pillows and brass pots."

"We believe in having fun with our money," Rene'e adds.

"Come see my bears," she says, suddenly tugging on arms and searching for a set of keys to unlock the 15-foot-high crates in what was once the middle of the du Pont living room. A brown kodiak and a white polar, in upright attack position, stare out through glass eyes -- frozen, more than 100 years ago, by a Victorian taxidermist.

"Take some pictures of me with the bears," Rene'e commands as she climbs through the narrow opening in the crate and into the arms of a bear.

"Kong," she says. "Fang. Fang. Fang."

"Look," she says, "just like Fay Wray."

Trupin looks on proudly.

"I mean, isn't there something in the Constitution about a man's home being his castle?" Barry Trupin wants to know.

"With any luck, and given cyclical hurricanes, the whole thing will be blown away by Christmas," Charlotte Harris prophesies.

"The Trupin Affair," say lawyers for both sides, will likely run on well into the dark winter months. Whatever the outcome, by the summer of '85 no doubt a new controversy will rage behind the green walls of sheared privet out here by the sea. CAPTION: Pictures 1 through 3, Dragon's Head; Barry & Renee Trupin at Dragon's Head, the $25 million castle they've been building for four years in Southampton, N.Y.; Charlotte Harris. Photos by Jeffrey C. Bennett for The Washington Post