He was the brother of “the Arab” killed by the infamous Meursault, the antihero of Camus’s classic novel. Seventy years after that event, Harun, who has lived since childhood in the shadow of his sibling’s memory, refuses to let him remain anonymous: he gives his brother a story and a name—Musa—and describes the events that led to Musa’s casual murder on a dazzlingly sunny beach. …