The greatly anticipated new novel by Norman Rush—whose first novel, Mating, won the National Book Award and was everywhere acclaimed—is his richest work yet. It is at once a political adventure, a social comedy, and a passionate triangle. It is set in the 1990s in Botswana—the African country Rush has indelibly made his own fictional territory. Mortals chronicles the misadventures of three ex-pat Americans: Ray Finch, a contract CIA agent, operating undercover as an English instructor in a private school, who is setting out on perhaps his most difficult assignment; his beautiful but slightly foolish and disaffected wife, Iris, with whom he is obsessively in love; and Davis Morel, an iconoclastic black holistic physician, who is on a personal mission to “lift the yoke of...