Less than three months into his vice presidency, Harry Truman is catapulted into the Oval Office following the sudden death of Franklin D. Roosevelt. As he recites the oath, he learns a chilling secret known only to a select the United States is on the verge of deploying a weapon of unimaginable power. This weapon could end the war but also herald a new age of global fear and uncertainty. Drawing from over twenty-five oral history archives across the US, Japan, and Europe, Graff has masterfully blended the memories and perspectives from key figures like Harry Truman and J. Robert Oppenheimer, the crews of the B-29 bombers, Enola Gay and Bock’s Car, and the haunting stories of those at ground zero in Hiroshima and Nagasaki, including the experiences of the hibakusha—the “bomb-affected people”—and the rescuers who bravely faced the devastation. Enriched by memoirs, diaries, letters, official documents, and news reports, this is an immersive and deeply human account of the then-secret Manhattan Project through the end of World War II and the dawning of the Cold War, capturing the scientific breakthroughs, military decisions, and profound ethical dilemmas that emerged from using nuclear weapons.