Book excerpt: In a malarial outpost in the South American rain forest, two misplaced gringos converge and clash in this novel from the National Book Award-winning author. Martin Quarrier has come to convert the elusive Niaruna Indians to his brand of Christianity. Lewis Moon, a stateless mercenary who is himself part Indian, has come to kill them on the behalf of the local comandante. Out of this struggle Peter Matthiessen creates an electrifying moral thriller—adapted into a movie starring John Lithgow, Kathy Bates, and Tom Waits. A novel of Conradian richness, At Play in the Fields of the Lord explores both the varieties of spiritual experience and the politics of cultural genocide.