"The Sympathizer" (Coutesy of Grove/Atlantic/Coutesy of Grove/Atlantic)

Forty years ago this month, after a long, deadly release of flatulence from American politicians, the United States evacuated its personnel from Saigon in an operation appropriately code-named Frequent Wind. Whether you were alive then or not, the images of those panicked Vietnamese crushing the U.S. Embassy are tattooed on our collective consciousness.

In the opening ­pages of Viet Thanh Nguyen’s extraordinary first novel, “The Sympathizer,” that terror feels so real that you’ll mistake your beating heart for helicopter blades thumping the air. Nguyen brings us right inside the barbed-wire-encircled home of a South Vietnamese general just waking from his faith in American resilience. Thrashing all around him, officers and cronies are bargaining for survival: Who will get out? Who will be left to the hands of their inexorable enemy?

The General doesn’t know it, but the captain he’s put in charge of those decisions is, in fact, a Viet Cong spy. “Every stroke of my pen through a name felt like a death sentence,” says this unnamed narrator, who has burrowed deep into the General’s confidence. “I could not help but feel moved by the plight of these poor people. Perhaps it was not correct, politically speaking, for me to feel sympathy for them, but my mother would have been one of them if she were alive.”

Over the next 350 pages, that conflicted whisper draws us through what is surely a new classic of war fiction. ­Nguyen, who was born in Vietnam and raised in the United States, has wrapped a cerebral thriller around a desperate expat story that confronts the existential dilemmas of our age. Startlingly insightful and perilously candid, the narration comes to us as a confession written and rewritten many times in an isolation cell. The imprisoned captain recalls fleeing with the South Vietnamese general and insinuating himself into the refugee community that settles around Los Angeles. There, he continues spying on the restless warriors as they plot a quixotic plan to liberate their homeland from the communists.

Given that explosive opening scene strafed with bullets and punctuated by bombs, the rest of the novel should feel comparatively tepid, but it never does because the captain’s serpentine voice is so hypnotic and the events he relates are so captivating. A careful student of American literature with a well-tuned ear for pathos, irony and the rhythms of English, he’s just as adept with a Roth-inspired comic scene of self-abuse as he is with a gorgeous Whitmanian catalogue of suffering. His captors want a confession written in the well-worn phrases of ideological purity, but he resists on stylistic grounds raised to the level of moral imperative: “It seemed as much of a crime to commit a cliche to paper as to kill a man.”

“The Sympathizer” is the first novel by Viet Thanh Nguyen. (Grove)

It’s the captain’s special burden that the quality that makes him such an effective spy — namely, his boundless sympathy — is the same quality that infects him with guilt. As an observer, he’s brilliant; as an assassin, he’s hobbled. “They were my enemies,” he says of the men he is regularly betraying, “and yet they were also brothers in arms.”

Once in California and relieved from the exigencies of war, he turns his incisive wit on American culture and its cheery racism. Sometimes, he poses as an innocent abroad, as when he watches “The Jeffersons,” “a TV comedy about the unacknowledged black descendants of Thomas Jefferson, America’s third president and the author of the Declaration of Independence.” But usually, he’s more direct. “Although every country thought itself superior in its own way,” he asks rhetorically, “was there ever a country that coined so many ‘super’ terms from the federal bank of its narcissism, was not only superconfident but also truly superpowerful, that would not be satisfied until it locked every nation of the world into a full nelson and made it cry Uncle Sam?”

A right-wing congressman courting the exiled South Vietnamese military comes in for some exquisite satire, but the novel’s most complex comedy and cultural criticism stem from the captain’s work on a Hollywood movie called “The Hamlet.” Hired as “the technical consultant in charge of authenticity,” our genial narrator quickly finds himself enslaved in the Philippines on a project you’ll recognize (“Apocalypse Now”). As funny as it is tragic, this section alone could carry the whole novel. (The Thespian — clearly Marlon Brando — makes a hilarious, reeking cameo before his much re-filmed death scene in which he groans, “The whore! The whore!”)

“The Sympathizer” is laced with insight on the ways nonwhite people are rendered invisible in the propaganda that passes for our pop culture. In ­Nguyen’s version, the Francis Ford Coppola character is not just a monumental ass, he’s also a latent racist determined to make a film that pretends to mourn America’s struggle, but in fact reinscribes its grandiose purity. “The Movie was just a sequel to our war and a prequel to the next one that America was destined to wage,” the captain laments. “Killing the extras was either a reenactment of what had happened to us natives or a dress rehearsal for the next such episode, with the Movie the local anesthetic applied to the American mind, preparing it for any minor irritation before or after such a deed.” With its cinematic explosions, abuses and killings, this deconstructive portrayal of the Academy Award-winning classic provides a bracing dramatization of the way American hegemony and romanticism are encoded in our most popular export.

But then Nguyen turns the screw another rotation, and the grotesque scenes in the Auteur’s movie lead into an extended examination of torture in real life. Yes, there are gang rapes and slow electrocutions and all the other ghastly tools of the trade here, but what’s particularly striking is the way Nguyen concentrates on that species of psychological abuse that our creative lawyers contorted into legal shapes during the Iraq war. I haven’t read anything since Orwell’s “Nineteen Eighty-Four” that illustrates so palpably how a patient tyrant, unmoored from all humane constraint, can reduce a man’s mind to liquid.

The contemporary relevance of this devastating final section can’t be ignored, but “The Sympathizer” is too great a novel to feel bound to our current soul-searching about the morality of torture. And it’s even more than a thoughtful reflection about our misguided errand in Southeast Asia. Transcending these historical moments, Nguyen plumbs the loneliness of human life, the costs of fraternity and the tragic limits of our sympathy.

Charles is the editor of Book World. You can follow him on Twitter @RonCharles.

On May 6 at 7 p.m., Viet Thanh Nguyen will be at Politics and Prose Bookstore, 5015 Connecticut Ave. NW.

THE SYMPATHIZER

By Viet Thanh Nguyen

Grove. 371 pp. $26