One was captivated by Soviet communism, the other by the soul of Russian music. One betrayed his country, while the other forged a lifelong connection to the Russian people with his dazzling interpretations of Tchaikovsky.

The lives of these two Americans caught up in the great geopolitical dramas of the 20th century — Noel Field, a State Department diplomat turned Soviet spy, and Van Cliburn, the virtuoso pianist who became a cultural hero during the Cold War — are the subjects of two entertaining, intriguing new books.

In “True Believer: Stalin’s Last American Spy” (Simon and Schuster, 288 pp., $27), Kati Marton richly documents the story of the Swiss-born, Harvard-educated Field. A “sensitive, self-absorbed idealist and dreamer,” he progressed from pacifist liberal to secret agent whose belief in communism proved perversely unwavering. Using Field’s letters and papers, as well as a trove of other documents from KGB archives, Marton, author of “Enemies of the People,” builds a detailed narrative with twists and turns galore.

Outwardly the tall, WASP-y Field looked every inch the government official as a young hand at the State Department in the late 1920s. But like many of his generation, Field embraced communism during the economic collapse of the Depression; by 1936 he had been recruited into the murky world of espionage. Field rationalized his treasonous betrayal as a noble endeavor: “I had become conscious of the fact that the task [of spying] is an honorable duty,” he later observed.

Field’s combination of earnestness and naiveté served him well — up to a point. He connived in the murder of defectors but was tone deaf to the disputes and doubts that embroiled Western communists. Field dedicated his life to the movement he passionately believed in — but was ultimately expendable.

After World War II, he traveled through Eastern Europe, where he hoped to build a new society. Instead, he found himself plunged into a Kafkaesque nightmare. Kidnapped by Czech security services in Prague in 1949, he was turned over to Hungary. Accused of plotting against Moscow, Field was tortured and imprisoned, despite his repeated declarations of loyalty to Stalin.

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His fate also drew his family into the net. Field’s brother and wife were both jailed in Eastern Europe after they attempted to find him. Marton’s account of their fates is poignant and almost defies belief. Like the man at the center of this extraordinary story, they could not fathom the sinister side of Stalinism, even as it closed in all around them.

A tall, boyish Texan with a famous mop of curls, Van Cliburn was an innocent of another sort. His love of all things Russian was on display for the entire world to see. At 23, he took Moscow by storm, winning the First International Tchaikovsky Competition in 1958. His performances were otherworldly — so passionate and intuitive that Russians embraced him as one of their own. Even Nikita Khrushchev, the Soviet Union’s fiery premier, was bowled over.

In “Moscow Nights: The Van Cliburn Story — How One Man and his Piano Transformed the Cold War” (Harper, 452 pp., $28.99) Nigel Cliff, author of “The Shakespeare Riots,” brings a melodramatic touch to his portrait of Cliburn, “a gregarious charmer obsessed with privacy, a model of piety with a rebellious streak, a driven man who could be hopelessly dysfunctional, a patriot who loved Communist Russia, a man-child who was old when young and young when old.”

Mixing accounts of Cold War incidents that brought the Soviet Union and the United States close to real war — the downing of U-2 pilot Gary Powers, the Cuban missile crisis — Cliff shows how Cliburn became a bridge between East and West.

Cliburn’s triumph was a rebuke to Soviet charges that Western capitalism equaled crassness. At the same time, Cliburn’s victory allowed the Soviets to say they put art above politics. It was a propaganda coup for both sides.

Cliff’s prose is as breathless as his subtitle. Still, Cliburn emerges as a conflicted man in the middle. His love of Russian culture was genuine: “These are my people,” he told a reporter. “I guess I’ve always had a Russian heart.” To his legions of fans — Cliff compares Cliburn to Elvis Presley — he was “Vanya Kleeburn.” He recorded with the Moscow State Symphony and toured the United States to acclaim.

But he was fated to endlessly recreate his winning program — Tchaikovsky’s First Piano Concerto and Rachmaninoff’s Piano Concerto No. 3 in D Minor. Cliburn was possessed by Russian music, but, as Cliff suggests, his artistic evolution peaked during those famous days of 1958.