Author and historian Iain MacGregor profiles a diverse range of players in his latest book about the first atomic bomb used in warfare. MacGregor uses visually enticing description and lively dialogue to draw readers into key actors’ personal stories in “The Hiroshima Men: The Quest to Build the Atomic Bomb, and the Fateful Decision to Use It.” The men include award-winning writer John Hersey, bomber pilot Paul Tibbets Jr., scientific theorist J. Robert Oppenheimer and Hiroshima Mayor Senkichi Awaya.