[13] Set as the flashback in a coerced confession of a political prisoner, the book tells the story of the South Vietnamese Government in 1975 and subsequent events in American exile in Los Angeles, through the eyes of a half-Vietnamese, half-French undercover communist agent.

[14] The spy remains unnamed throughout the novel from the fall of Saigon, to refugee camps and relocation in Los Angeles, to his time as a film consultant in the Philippines, and finally to his return and subsequent imprisonment in Vietnam.

During the imminent fall of Saigon, he, as an aide-de-camp, arranges for a last minute flight as part of Operation Frequent Wind, to secure the safety of himself, his best friend Bon, and the General he advises.

The continuous emasculation and dehumanization within American society prompts the General to draft plans for assembling an army of South Vietnamese expatriates to return as rebels to Vietnam.

While participating in the expatriate unit, the narrator takes a clerical position at Occidental College, begins having an affair with Ms. Mori, his Japanese-American colleague, and then the General's eldest daughter, Lana.

While living in the United States, the narrator sends letters in invisible ink to Man, a North Vietnamese revolutionary and handler, providing intelligence about the General's attempts at raising a commando army.

He refuses to show only one side, he leaves nothing out (even his painful memories of a childhood without a father or of his first experience masturbating), and he sympathizes with the many perspectives of a complicated conflict that has divided a nation.

[10] In part, the novel is a response to Nguyen's own admiration of, but difficult relationship with, works like Platoon, Apocalypse Now, and Rambo and the slaughter of Vietnamese in the films.

[19][20] The New York Times Book Review praised the novel for its place in the broader Vietnam War literature, and for its treatment of dualities in a way that "compares favorably with masters like Conrad, Greene and le Carré".

[10] Writing for The Washington Post, Ron Charles called the novel "surely a new classic of war fiction" which is "startlingly insightful and perilously candid".

[16] For Charles, it is less the particulars of the thematic explosion of the response to the Vietnam war that makes the novel relevant, but rather how "Nguyen plumbs the loneliness of human life, the costs of fraternity and the tragic limits of our sympathy".

[16] Randy Boyagoda, writing for The Guardian, describes it as a "bold, artful and globally minded reimagining of the Vietnam war and its interwoven private and public legacies".

[24] Though generally supportive of the novel, Boyagoda describes this overwriting: "the Captain's grandstanding against east/west stereotypes and against the putative ills of the US and Catholicism clogs his monologue because it does little more than advance an equally hackneyed set of complaints and rebuttals.

"[9] The Sympathizer was selected for more than 30 best-of-the-year lists, including The New York Times, The Wall Street Journal, The Washington Post, The Guardian, and The Globe and Mail.