BOOK REVIEW : The Spy Who Came in for the Cold War : THE SPY WHO SAVED THE WORLD; How a Soviet Colonel Changed the Course of the Cold War, <i> by Jerrold L. Schecter and Peter S. Deriabin</i> , Charles Scribner’s Sons, $24.95, 352 pages

“The Spy Who Saved the World” has all the qualities of a thriller by John LeCarre, but this tale of espionage in the chilliest years of the Cold War is not a novel. Rather, it is a revisionist expose of Oleg Penkovsky, a real-life spook whom the authors hail as “the greatest Soviet spy to serve the West after the end of World War II” and “a fearless prophet . . . fired by injustice to himself and the Russian people.”

When Penkovsky first offered to sell his country’s secrets to the CIA and Britain’s MI6 back in 1960, he was a 41-year-old colonel in Soviet military intelligence at a moment of crisis. Disaffected, frustrated over his meager pay and lack of prospects, hungry for respect and restless for adventure, he threw himself at Western businessmen, diplomats and tourists for nearly a year before someone in the CIA finally paid attention to him.

“I am your soldier,” he told the cautious agents who secretly debriefed him during a visit to London with a Soviet trade delegation. “I respect and love the United States.”

The CIA suspected that Penkovsky was a mole planted by the KGB or perhaps just a crank--and some of his wackier notions must have encouraged their suspicions. For example, Penkovsky was obsessed with the idea of planting small nuclear devices near the command-and-control facilities of the Soviet armed forces in anticipation of some future “H-Hour” when the superpowers would finally go to war.

“The weapons should be small enough to be put inside a little suitcase . . . and left next to a house,” Penkovsky insisted gleefully. “Then, when the leaders . . . are all destroyed . . . they will have to use some old, sclerotic goats, not fit for military duty.”

When Penkovsky finally convinced his handlers that he was not acting at the direction of the KGB--a point that authors emphasize throughout the book--they put him to work at securing top-secret information from the highest circles of Soviet military intelligence. And, as the hyped-up title of the book suggests, the authors credit Penkovsky with supplying the crucial data that enabled John F. Kennedy to “manage” the Berlin crisis of 1961 and the Cuban missile crisis of 1962 without triggering a nuclear war.

“No Soviet spy has provided more material or had a greater impact on history,” the authors repeatedly argue.

“He changed the West’s perception of Soviet nuclear weapons; he helped the Free World to understand the inadequacy of the Communist system. He provided the hard specifics of Soviet military strength and weakness. He identified for the West the vast Soviet intelligence apparatus: how it worked, who were its agents, their assignments and priorities.”

More convincing than these grandiose claims--and vastly more compelling to the reader--is the insider’s view of how Cold War espionage really worked. Some of the nuts and bolts are what we expect: dead drops, spy cameras, radio codes, contact poisons, and the other paraphernalia of a spy thriller. But we also glimpse some of the odder and more telling secrets of “tradecraft.”

The very first task assigned to Penkovsky, we learn, was to look through about 7,000 photographs of suspected Soviet intelligence officers and identify them to his case officers. And one of the most crucial secrets that Penkovsky delivered to the CIA came not from the painstaking and perilous work of photographing documents with a miniature camera, but rather from a drunken remark overheard at a birthday party for Soviet marshal.

Penkovsky is portrayed as a troubled and enigmatic fellow whose motives are never quite clear: “I am sly,” he told his case officers. He claimed to be a selfless freedom fighter, but he bargained hard for perks and payoffs, including a new set of false teeth and a $250,000 trust fund.

Of necessity, he labored in obscurity--but he demanded to meet the Queen of England. And we are given the comic but poignant scene in which Penkovsky’s handlers, in order to soothe his hurt feelings, presented Penkovsky with his own set of American and English uniforms (he preferred the American one because it was bedecked with medals and ribbons).

What is most remarkable about “The Spy Who Saved the World” is the degree of access to both the CIA and the KGB that the authors enjoyed. Transcripts of secret CIA debriefings are quoted at length, and the authors describe an extraordinary on-the-record interview with a high-ranking KGB official--”a Soviet version of George Smiley”--who hosted a screening of the KGB surveillance film that led to Penkovsky’s arrest and revealed the details of Penkovsky’s secret execution.

“Penkovsky was not motivated by any political ideas toward peace or any other humanitarian ideals,” the KGB official told the authors, “but by maliciousness, distorted self-pride, ambition, and personal immorality.”

“The Spy Who Saved the World” may have a certain antique quality, but it is still a rich, authentic and evocative story of espionage in the real world. And the very fact that the book exists at all is one of the curiosities of the latest upheavals in the world order.

Next: Richard Eder reviews “Paradise News” by David Lodge (Viking) .