The moment Arkady Nikolaevich Shevchenko left his apartment on New York's East Side one spring night in April 1978 and rode off in a sedan driven by agents of the CIA, he became a hot commodity, prized by the intelligence and publishing communities alike. As the highest ranking Soviet official ever to defect, he was an instant superstar.

Everything has worked out for Shevchenko. He is the author of "Breaking With Moscow," which has been on The New York Times best-seller list for 15 weeks. He is constantly invited to lecture, often for $10,000 or more. There is talk in Hollywood of making a movie of the Shevchenko story; rights could sell for about $500,000. The CIA has been paying him $60,000-a-year-for-life ever since he defected, though one agency source said, "They'll probably cut the money off at some point. He might have more now than the CIA."

But there are lingering questions of how valuable Shevchenko has proved for those who were most enthralled by his presence. In the intelligence community, some agency sources were disappointed with the information he provided. Some thought the level of his information did not match his rank in the Soviet bureaucracy.

And after having been the subject of a war between the KGB and the CIA, Shevchenko took his place in the middle of New York's hottest publishing war: Simon & Schuster versus Random House and its subsidiary, Alfred A. Knopf. Simon & Schuster, which had promised Shevchenko $600,000 for the book in 1978, turned it down a year later. Too dull and too late, the publisher said. Now Simon & Schuster is second-guessing the best-selling manuscript Shevchenko produced this year for Knopf. S & S is wondering if, in one editor's words, Shevchenko didn't "juice up" his story to make it more commercially appealing.

In the meantime, Arkady Shevchenko is a peripatetic celebrity. He is free, wealthy and getting wealthier.

"Arkady's been whizzing around the country concocting an impossible schedule of promotions and interviews as he goes," said Shevchenko's lawyer and confidant, William Geimer. "It's been fast and furious for months. After so long in the wilderness, he's feasting on the attention. It's a binge of sorts."

Shevchenko is now on vacation abroad. After repeated calls to his office, Shevchenko told his secretary he did not want to be interviewed for this article. Through his secretary, he did say, "People will believe what they want to. I've been under attack before. . . . I'm not a politician and I'm not running for public office."

Although he has written opinion pieces for The Washington Post in the past, he also stated that the newspaper "is detrimental to the interests and the security of the United States in its liberal attitudes."

Geimer said, "Arkady sounds like he's overdone the travel and worn himself out."

Six months after the defection, Simon & Schuster's editor-in-chief Michael Korda signed Shevchenko to a contract that called for a guaranteed advance of $600,000 and a completed manuscript by September 1979.

On the basis of five early chapters, the publisher pronounced the book "unsuitable" in the spring of 1980. Simon & Schuster demanded Shevchenko return what had already been paid him -- $146,875 plus $16,890.62 a year in interest on a 10-year payment schedule. Shevchenko's lawyers filed a $15 million counterclaim but lost.

Shevchenko's lawyers questioned why the manuscript was rejected but were never satisfied with the answer. One source who helped with the manuscript said, "Simon & Schuster's problem with it was that the book was incredibly dull. There was no drama or animation to it. And he couldn't write. The stuff was always late, too."

Said Korda, "I turned it down because A) it was not interesting, B) it was not worth the money we had paid for it and C) he did not deliver the inside stories on the top-level Soviet officials we had expected."

Although it took constant revision, Knopf got a lot more for a lot less. For no more than a third of what Simon & Schuster had paid, Shevchenko produced a best seller. Korda says he was not embarrassed, but the two publishers are in a veritable war over best sellers and Simon & Schuster cannot have taken the loss lightly.

What made the difference between the wooden, largely academic book Shevchenko began writing for Simon & Schuster and the anecdotal best seller he ended up writing for Knopf was a lengthy description of how Shevchenko had worked as a spy for the CIA 32 months before he finally defected. In the work Shevchenko had submitted to Simon & Schuster there had been no mention of his years as a source for the CIA.

"You can assume there were security inhibitions originally," said one intelligence source. "Spying for the CIA, that's treason, and a KGB assassination squad knows what it's doing. The agency couldn't have thought it desirable to have it out, either."

Said the book's editor at Knopf, Ashbel Green: "I'm not even sure if Simon & Schuster even knew that Shevchenko had had a relationship for more than two and a half years with the CIA."

Simon & Schuster's Korda says he is "slightly suspicious" of the present manuscript: "It wasn't just because he never mentioned the CIA and the espionage material. The material changed, too. For example, he had told us that he would deliver a very intimate chapter on Khrushchev but when we got it, it wasn't very interesting at all. Now the chapter on Khrushchev is very intimate.

"That kind of thing makes me think that Shevchenko's experience with Simon & Schuster made him and his people think they'd better juice it up a bit."

"It's funny," said Geimer, "because the one chapter that changed least was the Khrushchev chapter. Korda said 'Keep it like it is.' He thought that was the best chapter!"

The secret of Shevchenko's work for the CIA before his defection -- what became known among Geimer and Shevchenko as "our spy story" -- began to leak from sources in Congress and intelligence.

It didn't help matters any when a call girl named Judy Chavez told an NBC reporter in October 1978 how she had been paid thousands of dollars a month to have a "relationship" with Shevchenko in the months following his defection. She said Shevchenko had admitted to working for the CIA; she, in turn, made his confession public. Chavez later described it all in a quickie memoir, "The Defector's Mistress."

The Chavez affair was only part of a tumultuous period that followed defection. When Soviet security agents discovered that Shevchenko had bolted his job at the United Nations, they quickly took his wife back to Moscow. She died weeks later under mysterious circumstances. Shevchenko maintains that the KGB murdered her. The Soviets say she committed suicide.

Shevchenko also drank heavily at times in the months preceding and immediately following his defection but he has now stopped. Geimer introduced Shevchenko to a court stenographer named Elaine Jackson in late 1978. They married within two months and she left her job to help Shevchenko write "Breaking With Moscow."

"With the Chavez thing and the stuff about his drinking, Shevchenko's integrity was in doubt," Geimer said. "We figured that by not saying anything about the spy story, we were denying it. So we decided to come out with it and save a lot of the academic material for later books."

Said Green, "When Simon & Schuster turned it down, Shevchenko and his lawyer Geimer discussed what they had to do and, offering it to another publisher, they decided to enlarge the story. When they came to us in midsummer of 1980, they went to Marc Jaffee, who was then the head of Ballantine Books. Marc knew I was interested in things Russian and passed it on to me.

"The whole thing took an incredibly long time, nearly four years."

Shevchenko thanks his wife, Geimer and Green in his book's foreword -- no one else by name.

However, sources said that Alfred Friendly Jr., a Washington writer, was paid $50,000 to work on Shevchenko's manuscript. Friendly, the sources said, worked for 15 months on the book but Knopf was not satisfied with his version either. Both Friendly and Green refused comment on the subject, though Green did say, "Shevchenko, Geimer and I agreed that we wouldn't mention anyone outside of the three of us."

The final versions were a collaborative effort. Green was instrumental in providing the "sandwich" structure of the book -- beginning and ending with "the spy story" with a long middle section on the author's experiences in the Soviet Union and at the United Nations.

Officials at Knopf kept the manuscript a well-guarded secret.

"We were concerned about Shevchenko's security," Green said. On Knopf's lists of upcoming books, Shevchenko's book was noted as "Untitled By Anonymous."

When it finally did appear last February, "Breaking With Moscow" got the send-off publicists dream about: a full segment on "60 Minutes" and two long excerpts in Time magazine. Time paid between $25,000 and $30,000 for the excerpts.

Since publication, Shevchenko has been pushing his book as hard as any diet doctor or exercise guru.

"He's exhausted," Green said. "We're working him to death. He was just in London and Paris and running around doing everything."

Despite the CIA's retainer to Shevchenko, said Green, "No CIA guys ever got in touch with me. I was assured by Geimer that there was no necessity for the agency to review the book ."

Intelligence sources all agreed that there is nothing sensitive to be found in the book.

The principal appeal of "Breaking With Moscow" stems from the West's fascination with the Soviet Union and Shevchenko's ability to describe from personal experience the atmosphere at a Politburo meeting, Nikita Khrushchev's antics on a cruise or the voracious shopping habits of Foreign Minister Andrei Gromyko's wife Lidiya.

"He was the highest-level defector we've ever had," said Sen. Daniel P. Moynihan, who was ambassador to the United Nations and one of only a few U.S. officials aware of Shevchenko's status with the CIA. "It was more dramatic when Stalin's daughter came out, but this man sat behind Gromyko at Politburo meetings. We've never had anybody like that before!"

Not everyone agrees with Moynihan about the quality of information Shevchenko provided. Highly placed intelligence sources in the CIA and Department of Defense who interviewed Shevchenko after his defection say that Shevchenko, an undersecretary general at the United Nations at the time of his defection, had little information to offer on codes, satellites, defense installations and other issues they had hoped to learn more about from a diplomat who calls himself an expert on arms and disarmament. Geimer himself said some intelligence officials complained that they had been "disappointed" with their debriefing sessions with Shevchenko.

One source who interviewed Shevchenko at length said he "got nothing" from the sessions.

"Shevchenko gave us an interesting look at the political hierarchy," another intelligence source said. "There have been far more interesting defectors in terms of information, but you've probably never heard of them."

Two sources who helped Shevchenko at various stages of preparing the manuscript said they thought the final work was generally accurate (insofar as such a work can be checked), but they both said they were "amused" at the portrait Shevchenko paints of his own power.

"He inflates his own role a bit," one said.

Adm. Stansfield Turner, who was Director of the Central Intelligence Agency from 1977 to 1981, said, "I personally interviewed him, knew him personally, and he had a lot to offer. I think sometimes people expect more from a defector than you're ever likely to get. The Soviet Union is a closed society and some of their people don't have the same information his American counterpart might have.

"You have to remember that Shevchenko was not an ambassador to the United States. He was an employe of the United Nations and so he had less access than an ambassador might."

Shevchenko no longer lives in "safe houses" with CIA surveillance as he did in the months following his defection. Numerous people know where he lives in Washington and the Soviets, no doubt, know too. Sources said Shevchenko had the option to go underground, to change his appearance and identity. But he refused and appears openly, in print, on television, at public lecterns. He has said that he did not want to go from "one prison to another prison."

Shevchenko has been told he has been sentenced to death in the Soviet Union.

But Stansfield Turner believes the Soviets will leave Shevchenko alone "because if any harm came, it would be embarrassing, too obvious who had done it."

Not everybody in the intelligence community agrees.

"When someone as important as Shevchenko defects, people in Russia hear about it," said one source. "And when a defector meets his demise, that news is circulated, too. Defection is not something to be encouraged and the Soviets are sure not to. It will not surprise me at all if Mr. Shevchenko has an early expiration. The KGB has a long memory."