Robert Service is a biographer’s biographer. His synoptic book (Belknap Press, 760 pages, $29.95) begins with “Stalin as We Have Known Him,” a chapter-long analysis of the biographies that have created “Stalin.” The name needs scare quotes because it is indeed an invention – an effigy Joseph Dzhughashvili perfected and a persona that generations of biographers have promulgated. Happily, what follows this interesting, if curious, introductory is a capacious narrative, the subtlest biography of Stalin so far.

Stalin first received biographical attention in the 1920s, just as he emerged victorious over Trotsky and other Bolshevik rivals for power. Winners, it is said, write history. True enough in most cases, but not so when Trotsky is the loser. This brilliant writer – and later his accomplished acolyte, Isaac Deutscher – portrayed Stalin as a mediocrity, even a dullard, unworthy of the Leninist legacy. According to them, Stalin was also a world-class schemer, a connoisseur of conspiracy who compensated for his paucity of ideas by enforcing his will through unremitting brutality and his one undeniable talent: He was an exceptional administrator, a bureaucratic mastermind.

In power, Stalin authorized biographies that lauded him, Mr. Service reports, as the “contemporary genius of world Communism.” His stature in the West grew as he became the Soviet Ataturk, modernizing his nation, educating its masses, and catapulting the U.S.S.R. into the front ranks of industrial nations.

Even when the Moscow trials of old Bolsheviks accused of treason temporarily diminished Stalin’s prestige, he had his loyal cohort of apologists arguing that Stalin was only preserving the state and protecting the Leninist revolution: The full story of his purges and the extent of the Great Terror that murdered millions had yet to be exposed. Likewise, Stalin’s pact with Hitler had its defenders. Yet, astonishingly, “Stalin as We Have Known Him” does not address the late 1930s at all.

Instead, Mr. Service segues to World War II, when, against expectation, the Red Army triumphed over a Nazi opponent so formidable that the Allies did not open up a Second European Front until 1944, after the Soviet victories over the invaders. Time magazine made Stalin Man of the Year, Mr. Service notes. Not until the onset of the Cold War did Stalin seem to Westerners, to his biographers, and to a later generation of Soviet leaders led by Khrushchev, a villain, a “power hungry killer.”

Stalin then became, in biographical accounts, the absolute ruler – more arbitrary and tyrannical than any czar and a staple of biography itself: “Hardly a year has passed since Stalin’s death in 1953 without the publication of yet another biography,” observes Mr. Service. Disturbing memoirs began to appear. Khrushchev released files that further sullied his predecessor’s reputation.

Mr. Service singles out the work of Roy Medvedev, a Soviet dissident in the 1960s who began documenting the massive scale of Stalin’s crimes. But, to my amazement, Mr. Service does not even mention Aleksandr Solzhenitsyn. Granted, the novelist is not a biographer or a scholar; nevertheless, he is a crucial source for “Stalin as We Have Known Him.” History and biography owe more to fiction like “The First Circle” – not to mention “The Gulag Archipelago” – than Mr. Service is willing to acknowledge.

Though Mr. Service pays tribute to his predecessors, he does not rank them.

He acknowledges his debt to the “political and psychological insights of Robert Tucker, Adam Ulam, Robert McNeal, and Ronald Hingley.” Robert Conquest, who has published more than a half dozen titles on Stalin and his period since the 1960s, including a full-scale biography, “Stalin: Breaker of Nations” (1993), is perhaps Mr. Service’s main competitor. But, in the latter’s view, Mr. Conquest focuses too exclusively on Stalin’s “unhealthy appetite … for vengeance and murder.”

Conquest and Medvedev led the way, Mr. Service notes, to a view of Stalin as, in part, a captive and product of intraparty politics. His biography, by contrast, aims to expunge the last vestige of the Trotskyist line that Stalin was a nonentity in pre-revolutionary Russia. Even before 1917, he argues, Stalin cut quite a figure among the Bolsheviks, and his ascent to power had a longer gestation than his detractors ever cared to investigate.

Not only has this biographer had access to recently opened archives, he writes with an exquisite sensitivity to the demands of both history and biography. His Stalin does not merely menace his people; he is a fallible ruler often hemmed in by the “machinery of the system” he operated. “He could modify it,” Mr. Service points out, “but he was unable to transform it without shelving the basis of ‘Soviet power.'”

Stalin’s “personal rule depended upon his willingness to conserve the administrative system he had inherited.” Even the long suffering Soviet people had their say: “He also had to assimilate himself in many ways to the mental outlook of the people of the Soviet Union if he wanted to go on ruling them without provoking revolt,” Mr. Service concludes. Rather than commander-in-chief, Stalin was the “custodian-in-chief of the Soviet order” and thus its “detainee.”

Perhaps Mr. Service becomes a little too zealous in his campaign to overturn “Stalin as We Have Known Him.” But his book, like Simon Sebag Montefiore’s recent “Court of the Red Tsar,” shows how even Stalin’s most extreme actions arose out of a court culture that constantly questioned the purity of its courtiers’ motives. Purges and witchhunts are inevitable in cultures built on true religion. Inquisitions are the only way to ascertain who is faithful.

Stalin was no great theorist, but Mr. Service and Mr. Montefiore again agree that Stalin was a genuine Marxist, and that many of his actions were the result of his worldview, and not just of his psychology. Although Mr. Service does not believe his subject was insane, he does describe a disordered personality damaged by a drunken, abusive father and a rather zealous mother who consigned him to the ruthlessness of a religious order that only brought out a sadistic and duplicitous streak in a man-child who relished crushing his enemies. (And Stalin did have enemies every step of the way. His elimination of the competition was no mere expression of paranoia, although Mr. Service does not gainsay the twisted nature of Stalin’s responses to his opposition.)

In the end, it is Stalin as an intricate human being that fascinates Mr. Service. Fortunately, he provides us with an explanation of why he has been able to write with so much critical compassion:

One personal experience in the course of the research stands out from the others. In December 1998, I interviewed Kira Allilueva, Stalin’s niece, in her flat in north Moscow … Kira Allilueva’s refusal to be embittered by her uncle’s imprisonment of her – and her zest for life and fun – is a vivid memory. On that occasion she presented me with a copy of her uncle’s poetry. … It was the first time I had met someone who had known Stalin intimately. … Kira Allilueva’s insistence that all the many sides of Stalin need to be understood before he can be comprehended is a principle that informs this book.

The kind of finely tuned balance the biographer establishes is evident in this early passage:

Stalin in many ways behaved as a “normal human being.” In fact he was far from being “normal.” He comported himself with oafish menace in private. But he could also be charming; he could attract passion and admiration both from close comrades and from an immense public audience. On occasion he could be modest. He was hard-working. He was capable of kindliness to relatives. He thought a lot about the good of the communist cause. Before he started killing them, most communists in the USSR and in the Comintern judged him to be functioning within the acceptable bounds of political conduct. … He was also an intellectual, an administrator, a statesman, and a party leader; he was a writer, editor and statesman. Privately he was, in his own way, a dedicated as well as bad-tempered husband and father. But he was unhealthy in mind and body. He had many talents, and used his intelligence to act out roles he thought suited to his interests at any given time. He baffled, appalled, enraged, attracted and entranced his contemporaries. Most men and women of his lifetime, however, underestimated Stalin. It is the task of the historian to examine his complexities and suggest how better to understand his life and times.

It is this notion of underestimation – the biographer’s burning desire to do justice to his subject – that excites attention and that Mr. Service exploits with considerable power.