It is 70 years since the advent of the atomic bomb, the most extreme weapon humankind has ever produced. Why did nuclear weapons spread across the Earth? The starting point was an intense spy war that took place in the midst of World War Ⅱ. With an eye to gaining a monopoly over nuclear weapons, the United States established a mysterious espionage unit called the Alsos Mission. Its purpose was to prevent Germany, the Soviet Union, and Japan from developing atomic bombs. What became of the spies and scientists who were caught up in the contest that would determine postwar supremacy? This startling story, based on newly found documents, is told through documentary and dramatic recreation.