This book succeeds in being many things to many people. It is a spy novel, as we follow the espionage twists and turns during the Manhattan Project. It is horror story, as chilling as any Hammer movie; we are told just how close the world came close to oblivion, before the Cuban missile crisis brought men to their senses. And it is a scientific exposition, in relative layman's terms, of how the physicists discovered the secret of the thermonuclear. Richard Rhodes' narrative keeps even technophobes hooked. The descriptions of how H-bomb tests exceeded even the anticipated yields are particularly chilling.