Squalid, spectacular, agitated, littered with ancient ruins and riddled with more spies than you can shake a cloak at, Central America seems almost too much of a good thing for a novelist: the treasure of the Sierra Madre tarted up for an apocalypse. Robert Stone, setting his new, now novel in an imaginary but circumstantial version of this place, is taking a serious risk; but the risk is worth it, and the wager is won. We are "south of cliché" here, as a character in the book says. Stone converts clichés into people, and people into questions. "A Flag for Sunrise" has the pace and suspense of a first-class thriller, and it catches the shifting currents of contemporary Latin American politics.

It is Stone's third novel. His first, "Hall of Mirrors," was set in New Orleans, chosen, Stone said, "because it is a city in which the...