If Knut Hamsun had died in 1935, at 76, only the pompous pastoralism that sullied his later work would have marred his reputation as Norway’s beloved Nobel laureate and Scandinavia’s greatest novelist. A fount of literary modernism, Hamsun — to whom Mann,Wells, Gorky, Hesse, Musil, Stein, Kafka, Gide, Brecht, Buber, Hemingway,and Henry Miller,among many others, gratefully genuflected — had, long before Joyce, laid bare the consciousness of the artist forging his soul in search of community. His egocentric misanthropy might have died with his family, friends, and publisher.

Jan Troell’s biographical film, “Hamsun” (1997), perversely begins in 1935, more than 40 years after he published his masterworks, “Hunger,” “Mysteries,” and “Pan,” and 15 years after he won the Nobel for his best-selling agrarian epic,”Growth of the Soil.” Mr.Troell is less concerned with Hamsun’s writings than with his role as the nation’s vaunted poet who outlived his instinctive genius and committed the error of acting on his politics: He backed Hitler.

An Anglophobe who spent a few early years wandering around the United States, Hamsun developed a fierce hatred for Yankees, Bolsheviks, and especially Britain (in the film, he rails at imperialist carnage in India and the concentration camps in South Africa), along with a corresponding admiration for efficient fascism. He supported Quisling’s plea for acceptance of the German invaders and offered up a few anti-Semitic nuggets that he apparently did not believe; Hitler’s obsession with Jews bewildered him.Yet even after Hamsun observed the slaughter spurred by Norway’s Reichskommissar, Josef Terboven, and was brusquely ejected from Hitler’s mountain aerie, he defended his actions, composing a front-page obituary for Hitler, that “great warrior for mankind.”

“Hamsun” is a long (154 minutes) and demanding film. The pace is deliberate and the dialogue elliptical, except when taken from the public record. Mr. Troell’s camera rarely moves; variety and emphasis are achieved through abrupt edits, close-ups, stock footage, and short pans. The combination of a calculated tempo and accumulation of incidents jars the film’s pulse. The last hour is taken up with the heavy days of Hamsun’s incarceration in an asylum, yet it never bores.

The film is very much about the relentlessness of time. Hamsun was fixated on always knowing the hour. One of the first close-ups is of his desk clock; the final scenes are punctuated by the winding and setting of clocks. For 17 years, until he breathed his last in 1952 (at 93), Hamsun whined about dying. His long-suffering family ruefully joked about his immortality pact with God.

In one astonishing scene, Hamsun collapses after chopping wood. He lies in the snow, knowing his time has come — and so consults his pocketwatch,which drops to his side.We are invited to contemplate the watch until a fresh flurry of snow revives him, at which point he reluctantly gets up and walks home. Later, his alcoholic daughter, Ellinor, maliciously throws his desk clock out the window. It shatters to the ground, but keeps on ticking.

Mr. Troell presumes recognition of Hamsun’s genius, which justifies the film’s gravitas and mania for detail.Yet he suggests nothing of the writer capable of mapping the absurdities of “Mysteries” or the dark burlesque of “Hunger,” except in sly references that only readers of the novels will recognize. In Hamsun’s big confrontation with Terboven, for example, much of his argument is taken verbatim from a stream-of-consciousness reverie in “Mysteries.” Only his stature is at stake here.”To think that the Nazis have such a magic flute at their disposal,” a publisher observes.

Per Olov Enquist’s exceptional script is faithfully based on Thorkild Hansen’s multivolume 1978 study, “Processen mod Hamsun,” which has yet to be translated.(The same wartime material is rehearsed in Robert Ferguson’s 1987 biography, “Enigma: The Life of Knut Hamsun.”) Hansen’s hugely successful book aroused controversy for digging up an episode that Norway and the rest of the world had succeeded in burying. American literary encyclopedias published in the 1950s and 1960s ignore, as if by fiat, Hamsun’s romance with Nazism.

In the late 1960s, Farrar, Straus began publishing new Hamsun translations, hoping to cash in on the mystical loner cache that had successfully revived Herman Hesse — they even used similar Milton Glaser cover art. The flap copy on “Hunger” doesn’t breathe a word about Hamsun’s indiscretion, but includes an introduction by I.B. Singer proclaiming Hamsun as the source for “the whole modern school of fiction in the twentieth century” and blaming his “tragic mistake” on his belief “that Nazism would spell the end of the left-wing radicalism which repelled him.”

Mr. Troell is less forgiving, but more ironic. Much of his portrait is devoted to the embattled marriage of Knut and Marie Hamsun, a joust that went on for more than four decades. The film gets under way with a ranting argument filled with expository details: Marie had sacrificed her theatrical ambitions and the welfare of their four children to the demands of his “great mind.”The Nazis, however, offered her stardom, traveling through Germany reading excerpts from Hamsun’s and her own stories. In the film, she is always heard reading the closing sentences of “Growth of the Soil,” which take on an increasingly baleful meaning. Marie, who died in 1969, was far more ardent than her husband and served three years in jail.

Mr. Troell cuts back and forth between Knut, forced to watch concentration-camp footage (his eyes reddening with horror), and Marie, forced to bare the most intimate details of her marriage to the detestable psychiatrist Dr. Gabriel Langfeldt, who thinks his devious probing will make him immortal. The suggestion arises that a bad marriage may have led to the Hamsun’s minor but by no means negligible contribution to the terror.

Yet no explanation is possible. Hamsun dislikes adulation of any kind; he knows, if no one else does, that he has no power and seeks none. Two boys for whom he pleads mercy are summarily executed by Terboven, whose own suicide is gleefully dramatized: in a slimy bunker, shared with a frog, the sodden monster murmuring “Heil Hitler” while igniting a dynamite fuse. Hamsun’s thinking, despite a candid courtroom statement, faithfully enacted, is incomprehensible.

The film’s most astonishing episode documents Hamsun’s encounter with Hitler (a journalist compares it to Goethe meeting Napoleon), beginning with his address in Vienna — Britain “must be crushed” — and a flight over Devil’s Mountain, before he shakes hands in chilling slow motion with the devil himself.They play out a grotesque comedy. Hitler wants to discuss art — does Hamsun get his inspiration early or late in the day? — and Hamsun wants to complain of Terboven’s tyranny. Hitler quakes like a time bomb before throwing him out.

The actors are splendid. Max von Sydow as Hamsun, the triumphant role of his later years, disappears into the part; Ghita Nørby as Marie, radiates the true believer’s shameless gleam. As Quisling, Sverre Anker Ousdal’s pasty, parchment skin exudes the viscosity associated with the name; Edgar Selge as Terboven is smarmily derisive; and Ernst Jacobi captures Hitler’s chuckleheaded chipmunk look.

The DVD, from the First Run Features catalog, is more problematic.The lackluster transfer is marred by a few visual distortions, skips, and a subtitle glitch.The imprinted subtitles, framed in black,suggest a less than scrupulous translation. The repeated lines from “Growth of the Soil” include an incomprehensible reference to “dots,” instead of Hamsun’s “specks.” Where Hamsun wrote, “All but nothing in all humanity, only one speck,” Marie reads, “She is hardly anyone among men. Only one.” Yet the availability of this film — a biopic to set beside Peter Watkins’s “Edvard Munch” — is a boon, requiring and justifying more than one visit.