AT ABOUT 3 p.m. on the afternoon of Aug. 16, 1977, the story of the century flashed across the orange groves and into the well-manicured jungle that surrounds the National Enquirer's headquarters in Lantana, Fla. Editor Iain Calder summoned his key aides to a closed-door strategy session, and simultaneously issued instructions to have a small jet made ready at West Palm Beach Airport.

Elvis Presley was dead. The Enquirer was mobilizing.

Associate editor Tom Kuncl, one of these invited to the fateful conference, stands about 72" high, weighs in at 215 pounds, wears a moustache, exhibits a quick, cynical sense of humor now and then, and generally employs pen and paper when he takes notes - in short, the characteristics widely associated with the species print journalist Americanus.

Kuncl is a former freelance writer who admits to experiencing "a lot of professional shock" when he joined the Enquirer in 1974. He now oversees the paper's four-man Washington bureau, and especially relishes what the Enquirer calls "government waste" stories - for instance, one about a grant to study the effect of native dancing on tourism in Haiti.

"I am just delighted that we live under a government that does these kinds of things," says Kincl. "I get these NSF grant lists and I am just a different man for a couple of days. I say, No, they're not really spending $150,000 on the mating habits of some species of shrimp in the upper Volta."

Kuncl was not, however, the most attentive or enthusiastic of the Elvis post-mortem conferees. "I just never did know sic'em about Elvis," he says. Plus he was in "a period of grief" over a story that Calder had just killed.

So Kuncl was quite taken aback when Calder looked across the desk and said, "Tom, what have you got going right now that's important?" The answer, as Calder knew full well, was nothing. "You go to Memphis," said Calder.

Kuncl was in the air at about 6 p.m., accompanied by four reporters and a photographer, while other Enquirer operatives were being flown in from other directions. Ultimately Kuncl, who viewed the assignment simply as "a good police beat story," would have a team of 20 working under him.

On arrival, his team tracked down the two fire department paramedics who had been the first outsiders to see Elvis in his deceased state. They were signed to an exclusive contract with the Enquirer, and whisked away to a hotel room to tell their stories. Several reporters from the Memphis newspapers, an assortment of band members, camp followers and groupies, and Elvis' stepmother Dee Presley were likewise located and (as required) put under contract.

"There was a lot of pragmatism in the air in Memphis which dovetailed with what I was there to do," says Kuncl.

Kuncl himself grabbed a yellow pages and turned to "P" for "psychics," where, sure enough, he found several listings, including one seer who has spoken to Elvis shortly before his death. Yes indeed, Elvis had had premonitions. ELVIS KNEW HE WAS GOING TO DIE

"Now it's hard for me to look you in the eye and tell you that this was a coup of some sort," says Kuncl, a man with only an average amount of interest in the supernatural - which at the Enquirer is much less than average. "But in fact it was.

"I'm not in charge of human nature," says Kuncl. "I just report it."

Once a death has been ruled the product of natural causes - as Elvis's was - Tennessee law forbids public disclosure of the findings of an autopsy. As a result, the 12 people present at the Presley autopsy - a list quickly complied by Kuncl's team - were unusually reticent when the Enquirer contacted them. But as every reporter knows, even a source who can't say anything generally says something. Thus an Enquirer reporter might ask a question like, "Doctor, isn't it true that his heart was extremely enlarged?" And a doctor might reply, "Well, I wouldn't say extremely . . ." and go on to give the exact dimensions.

"In the end we knew virtually every substance that was in (Elvis's) body," says Kuncl.

The Sept. 6 issue carried six pages of Elvis material. Among the revelations:

"In the months before his death . . . Elvis Presley surrounded himself with flunkies who submitted to violent and humiliating abuse" including karate kicks to the groin, but "dared not retaliate or even complain."

Elvis "was unable to pass a mirror without marveling at himself."

When his girl friend Ginger Alden found him slumped on the bathroom floor, "his eyes were closed and his face was a purplish color and swollen looking. His tongue was sticking out of his mouth and he'd bitten down on it."

But the biggest coup of all was the front-page photograph of "Elvis at Peace" - in his open coffin at Graceland. No one is telling just who took that picture or how many thousands of dollars the Enquirer paid for it. Vernon Presley, Elvis's father, said he was "heartbroken" after seeing the picture. "I have no idea who would have taken advantage of a family during this situation. I don't know anybody who would want to do that, but maybe someday we'll know."

What is public record is that the September 6 issue - according to the Enquirer - sold 6,688,563 copies, or nearly a million more than the previous best-seller, and issue that had u featured "The Amazing Appeal of 'Roots'" and "How Freddie Prinz Rehearsed His Own Suicide."

"I don't think Elvis was selling that well when he was alive," says Kuncl.

Even an average issue of the Enquirer (that's a figure of speech - no issue is average one sells more copies than any other weekly publication except TV Guide. Although its publisher is unable to offer a figure for the Enquirer's net worth, he adds that two years ago he turned down an offer to buy the paper for $50 million.

The Enquirer and its legions of readers are in the habit of meeting at the supermarket checkout counter these days, sometimes furtively. At 35 cents a copy (or about 20c a pound), the paper rates as one of the outstanding buys of any shopping expedition.

Inside a typical issue:

A voice-o-graph expert concludes that President Carter lied when he appraised the nation's economic condition as sound during his State of the Union message.

We learn that Charles Bronson, shooting a movie on bitter cold day in New York City, would not let his police escorts warm up inside Bronson's unused trailer.

Ten "leading psychics" predict 1978. One says Elizabeth Taylor will have a nervous breakdown and divorce John Warner (the connection between the two events is unspecified), while another says she will "enter politics, become an ambassador, and help settle the Israeli-Arab dispute." Yet another seer promises that "an Arab state will tow icebergs to the desert as a source of fresh water - and in one of them, stunned engineers will discover relics of an alien expedition whose members died in an Arctic ice storm."

We are told that, during a recent U.S. tour, a tyrannical Rumanian gymnastics coach refused to let Nadia Comaneci eat more than a piece of lettuce and a few slices of tomato a day.

An Enquirer reporter dressed up as a sheik from a mythical Arab island kingdom tells how he had senators and congressmen shamelessly kowtowing to him during an impromptu visit to the Capitol.

A flock of sheep have mysteriously sprouted grass on their backs, and there is a photograph to prove it. Says the caption: "Maybe, to paraphrase Greta Garbo, the animals 'just want to be a lawn.'"

For the people who produce it , as well as those who read it, the Enquirer is inextricably linked with the act of checking out. Going to work there, if you are some sort of newspaperperson, means checking out of the known world, taking a short ride on a UFO, and winding up on a preposterous, semi-tropical, journalist's funny farm.

Here reporters and editors live in oceanfront condominiums, are paid fabulous salaries supplemented by fabulous expense accounts, and scour the world in quest of the bizarre, the juicy and the uplifting.

"One of the biggest things I had to get accustomed to when I came here was spending money," says Kuncl. "Money is almost paper clips . . . We can easily be spending $20,000 for something that's going to end up in the traschan." Indeed, reporter John Harris was commissioned to conduct a worldwide search for utopia, at Enquirer expense, and returned six months later with the announcement that utopia, regrettably, had eluded him.

For a story about the escapades of some abscure Kennedy offspring the Enquirer will gladly stand the expense of a month-long stakeout. Or if more devious measures are called for, a reporter and photographer will descend on their quarry's preparatory school claiming to represent, let us say, "Soccer Digest," and will spend four hours chatting with soccer team simply in order to get two quotes from the unsuspecting young Kennedy who belongs to it.

The starting salary for an Enquirer reporter is $32,400 - about double what The New York Times pays. And the latest experiment in a long tradition of bizarre recruiting practices has been to hire reporters with absolutely no prior training or experience. "I want the next president of ITT. I want the next president of U.S. Steel," says Iain Calder, a Scotsman who is part of an ample contingent from the British school of newspapering. "People who are brilliant . . . people who are aggressive."

What he has gotten are Gail Birnbaum, Barnard College class of '76, Jessica Klein, Harvard '77, and Steve Chao, Harvard '77.

"I really don't believe it either," says Birnbaum, who spends much of her time on the road, supported wholly by an expense account, while she and Klein share minimal accommodations in Lantana. Before joining the Enquirer, Birnbaum's highest-paying job was for a public relations firm at $175 a week. She never worked for her school paper, the Columbia Spectator - "a serious omission on my part," she says - but has had several articles published in the Enquirer so far, including one titled "What Is Happiness?"

Generoso Pope Jr., owner, publisher and, by all accounts, the man in charge of the National Enquirer, has been saying for years now that his goal is a circulation of 20 million. It is a figure based, he explains, on achieving a readership comparable, when measured against total U.S. population, to that enjoyed by the most successful British national newspapers. Obviously, he has a considerable way to go yet, but he has come a way, too. Since 1952, when Pope paid $20,000 cash for the Enquirer, then a moribund New York weekly with scarcely aay staff, he has built circulation from 17,000 to nearly 6,000,000.

The best concise description of the brand of journalism currently practiced at the Enquirer is Calder's - "I keep telling the editors I'm looking for gee-whiz stories," he says. And nothing with limited appeal. In an accent that reeks of Glasgow and Fleet Street, Calder talks of reaching out to a typical Enquirer reader he calls "Missy Smith in Kansas City."

Nearly a million readers' worth of that growth has occurred just within the last year, spurred by the Enquirer's new TV advertising campaign.

Missy Smith does not like downbeat stories. She gets enough of those in her daily paper. So when people with crippling disabilities or terminal ailments find their way into the pages of the Enquirer, as they frequently do, we almost always discover that they are deriving renewed strength and hope from some wondrous medical innovation, from the attentions of family and friends, or from the stacks of cards and letters sent them by previously alerted Enquirer readers.

As for sex, "We try to do it in such a way that people almost won't notice it," says Calder. Violence has been out for about the last eight years, since the end of what Pope unemotionally calls the "blood and gore era" (when the Enquirer was known for such timeless headlines as "Mom Boils Baby and Eats It"). There is virtually no sports coverage - sports has limited appeal, explains Pope - and next to no politics.

Instead, the Enquirer runs on a blend of medicine, science and parascience stories; tales of personality quirks, feuds and affairs of the heart involving a select group of celebrities usually TV stars; first-person accounts of adventures and disasters; scandalous stories of government inefficiency and profligacy; and startling public opinion surveys.

British journalists, as a rule, start younger and with less formal education than their American counterparts, and earn less money. "I still pinch myself almost every month," says Calder, "because for someone from a little Scottish mining village . . ." The thought trails off, but Calder is presumably thinking of his salary as well as of his position - and he is presumably one of the four Enquirer executives who, according to Pope, draw salaries of $100,000 or more.

The Enquirer is full of "Brits," a category that encompasses Australians, South Africans and Irishmen trained on British papers. The virtues of some of the Brits are a popular topic of debate among the Enquirer's non-Brits. "They're great when it comes to 'Vicar Found in Love Nest," says one homegrown editor, "but if you want to know the implications of nuclear power you would be better off asking your parakeet . . ."

If there is friction - or merely heightened competition - between Brits and Americans at the Enquirer, it is probably not unintended. The same managerial tool was used to good effect, after all, when the Allies invaded Normandy. While other American workers worry about being replaced by machines, at the Enquirer they worry about being replaced by Brits.

Off-duty, the Brits are known as boaters, golfers and drinkers. A dartboard has been set up at one nearby bar to accommodate them, although "They're not very good at darts," says the bartender. "They think they are . . . we go along with it because it's just common knowledge that the British play darts."

A year and a half ago, Pope gave Ruth Annan, a cheerful, fast-talking, compulsively organized ex-Time correspondent, the task of making sure that stories in the Enquirer are - of all things - true. And she has attacked her assignment with enormous zeal, treating the unsubstantiated testimony of Enquirer reporters with approximately the same respect given an anonymous tip from a passing drunk.

The civil war that has ensued bears a certain resemblance to the plot of "The Battle of the Sexes," the movie in which an overbearing American efficiency expert, played by Constance Cummings, invades a backward Scotish textile mill run by Peter Sellers and Robert Morley. At one point in the movie, Sellers pays Cummings a late-night visit with murder on his mind, and she absentmindedly slams the kitchen door on th butcher knife he is about to plunge into her. There are people at the Enquirer who seem to harbor similar feelings toward Annan.

But Annan is regarded as enjoying the full confidence of her boss, who is the boss. So when she barrels into managing editor Paul Levy's office waving a dictionary and pointing out that he has used a word incorrectly, Levy is attentive. It is in a very subdued tone of voice that he notes that his dictionary and her dictionary appear not to see eye to eye on the matter. And he has nothing at all to say when Annan mentions how her dictionary, like all the volumes in the Enquirer's new reference library, was chosen with enormous care.

No, frontal attack is a doomed strategy in this war. A colleague may occasionally allow himself a snooty remark like, "Madam, perhaps you ought to be doing this story instead of me," but he must learn to play by the rules. (And it will invariably be a he, because Annan is the only high-ranking woman at the Enquirer.)

In moments of nostalgia, Enquirer reporters recall the era of innocence the preceded Annan's coming - when preposterous medical and scientific phenomena were vouched for by a cadre of "experts" who had "proved tractable in the past," as one ex-staffer puts it. And when, if an editor wanted substantiation, the reporter simply called up a second expert off the same list, who would be known in Enquirer parlance as the "second idiot."

But the Enquirer has become a fairly truthful publication in its middle age, the same reporter confides with a twinge of regret. Truthful, at any rate, given that it seeks out "gee whiz" type stories about UFOs, parapsychology, reincarnation, plus all manner of harrowing adventures - and frequently pays for what it prints.

A favorite Enquirer device is the "in the mind quote" - "my life flashed before me" and so forth - usually as told by the miraculous survivor of a brush with death. But here, too, standards are rising. Las year a story was killed, on grounds of implausibility, in which an 8-year-old Indian boy, who had been mauled by a tiger, was credited with the line, "The giant cat flashed his saber teeth," among other specimens of florid description.

Annan's proudest achievement, she says, has been the complete absence of libel suits since her arrival at the Enquirer. Two old $5-million suits are still pending, however - one filed by "Hong Kong hotel hostess" Marianna Liu, accused by the Enquirer of having had a romance with former President Nixon, and one filed by Carol Burnett, accused of having had an argument with Henry Kissinger in a Washington restaurant.

An eccentric institution, the Enquirer supports its share of eccentric individuals. There is, for instance, Dawson Taylor, a retired Ford dealer from Detroit who now works part-tima reading manuscripts for possible serialization - at the rate of 143 manuscripts a week, he calculates. Besides being a speed-reader, Taylor has a vocabulary of 200,000 words, by his owncount and is the author of "The Secret of Holing Putts," "The Secret of Bowling Strikes," "The Making of the Pope" and "Your Future in the Automotive Industry," among other books.

Senior reporter Bob Temmey, an inveterate outdoorsman who used to work for The Los Angeles Times, is the Enquirer's far-off-places correspondent. Temmey tracked a Polish mountain-climbing team to the 18,000-foot mark of Mt. Everest after hearing that its members had sighted the footprints of an abominable snowman. Whenever and wherever an earthquake occurs, Temmey will rush to the scene and locate that man, woman or child who has survived the longest, trapped under the most rubble.

Then there are the freelancers - for instance, Harold and Arline Brecher, a couple who reside in Reston, Va., and write stories about novel diets and psychic phenomena. And a father and son, Hal and Steve Jacques, both Hollywood-based celebrity watchers.

Celebrity stories are a world unto themselves, and the Enquirer has two distinct plans of attack when it gets the scent. The first plan is the stakeout - a team of reporters and photographers is commissioned to make pests of themselves gathering tidbits about, say, Raquel Welch's fling with a French actor.

In that particular case, Welch became so incensed that she plotted to elude her pursuers by booking a dummy reservation on a flight from Paris to New York when her real destination was Sardinia. But when Welch and her fling boarded their plane, according to editor Mike Hoy, they found an Enquirer reporter and photographer seated immediately behind them. There followed a "wild and ludicrous" two weeks in Sardinia, during which Welch and the Enquirer team changed hotels about four times. "It cost us both a lot of money," says Hoy wearily.

What resulted from these escapades was "RAQUEL WELCH'S NEW HUSH-HUSH ROMANCE":

"Raquel Welch is enjoying a hot new hush-hush romance with a dashing French actor, Andre Weinfeld. The couple has been together for over two months in Paris, sharing the same hotel suite, and behaving like 'lovestruck teen-ages.' But Raquel has gone to incredible lengths to shield Andre from publicity.

". . . This Enquirer reporter was on the plane with the couple when they flew off for a recent vacation on the Mediterranean island of Sardinia.

"They cuddled, kissed and carried on like two people very much in love during the flight.

"Then they went to a seafront bungalow and kissed, snuggled close and held hands while they sunbathed on the beach."

Elsewhere in the same story, Welch was quoted as telling an interviewer (not from the Enquirer), "It's too awful to see someone you love being devoured by publicity . . . I'm determined this won't happen with Andre." The Enquirer, the story proudly proclaimed, had "penetrated the wall of secrecy set up by Raquel."

The reason for all this unseemly behavior, of course, is the tendency of some celebrities not to talk to the Enquirer. But few celebrities can resist "senoir roving editor" Henry Gris, with his silver hair, continental manners and indeterminate accent.

"Hollywood is a laboratory of human stories," says Gris, who joined the Enquirer in 1969 after two decades with United Press International. "And the advantage of these human stories is that they are compressed into a very short period of time." Celebrities, like laboratory mice, have brief lives. "Hollywood is full of these beautiful white mice who fall from very high pinnacles of success . . . I am observer of the human stories and this is why I came to Hollywood."

"Some years ago," says an editor, "we were in a panic for a downpage story. Peter Lawford's wife had just left him. Gris called up Lawford and said, 'Wouldn't you say, peter, that this was the woman of your life?' "That's it exactly,' said Lawford."

More recently, James Coburn told Gris he had left his wife essentially because the time had come for him to enter a new seven-year life cycle.

During a recent conversation with Princess Grace, "We spoke about the way her daughter was being hounded by the press," says Gris. It apparently never occurred to the princess to hold Gris responsible for the fact that his employer, the Enquirer, has consistently had its hounds near the front of the pack. "She calls me Henry," Gris explains. "I call her Grace." Cary, Glenn, Kirk, Shirley, Audrey and Ingrid also call him Henry.

How does he do it? "I give the people something of myself," says Gris. "I have known so many fabulous people in the world . . . My range of interests is so wide . . . It's an exchange of thoughts, never just an interview." During a 40-year career as a journalist, he has exchanged thoughts with, among others, Hitler and Mussolini. "People know me, like me, enjoy me.

"I am very strict in mu moral code," he adds. "When a man suddenly changes his mind and says, 'I didn't realize, this is something I should not have told you,' I will honor that."

During the Spanish Civil War, for example, Count Ciano, Mussolini's son-in-law, "blurted out" to him the news that an Italian submarine had just sunk a Russian ship carrying supplies to the loyalists. Ciano phoned the next morning, however, to ask Gris not to print the story, and Gris obliged.

In 1945, he was "a tired war correspondent who wanted to stop all the nonsense of ducking bombs," so he went to work for UPI reporting American news - particularly of celebrities - for foreign newspapers. It was a "very specialized, very personalized a la carte service," he says.

In November 1958, Gris went to interview Tyrone Power, who was filming a movie in Spain. "He was vey depressed," says Gris, so "I spent the day telling him of my own experiences . . ."

"You are very generous," said Power when Gris had finished cheering him up.

A day later, Tyrone Power was dead, and Henry Gris had the last, if somewhat onesided, interview. "That was my lucky story," says Gris. "I had the feeling on that day that somehow he gave me back what he owed me."