Graham Greene's 1955 novel, set in the dying days of French colonial Indochina, is one of the foundational works of twentieth-century political fiction and a small masterpiece of moral ambivalence. Its narrator, Thomas Fowler, is a middle-aged British reporter in Saigon who has resigned himself to the pleasures of opium, his Vietnamese partner Phuong, and the protective stance of the professional observer. Into his world comes Alden Pyle, a young American attached to the U.S. economic mission, fresh from Harvard, full of ideas drawn from a thinker he calls York Harding about a 'Third Force' between French colonialism and Communist revolution. Pyle is courteous, earnest, and convinced of his own goodness. He is also, the novel slowly reveals, arming a Vietnamese splinter faction and complicit in a bombing in central Saigon that kills civilians. Greene, who had reported from Indochina and detested American postwar interventionism, built the book around Fowler's discovery that detachment is itself a moral position. The novel was widely misread on publication as anti-American polemic; it has been continuously vindicated by subsequent history, most obviously by the American war in Vietnam that began less than a decade later. It remains essential for readers thinking about good intentions, imperial innocence, and the costs of ideological certainty.