In 2016, Viet Thanh Nguyen’s novel “The Sympathizer” won the Pulitzer Prize. “The Committed” continues the story of the same hero—a former spy who has been burdened, all too inconveniently, with conscience and moral principles. In 1980s Paris, he encounters an exquisite society of intellectuals, works in a grim criminal underworld, and must face a tragic contradiction between the two people dearest to him—one that, perhaps, only death can resolve: the question is whose death, and under what circumstances.