Hiroshima was an event of such magnitude that it divided history into two periods: before and after the bomb. It led to the first day of a new age in which all life would be at risk. Almost seventy years later, as Peter Wyden began this book, the world was still dealing with the fallout of the bomb's creation.

Wyden draws on eyewitness accounts, interviews, and documents never before published in order to trace the nuclear state of the modern world to the historical roots of Hiroshima. Skillfully weaving together all the strands, stories, and characters, including the scientific, political, moral, military, and human viewpoints, Wyden provides a full understanding of how the bomb was created, why it was used, and what the aftermath of those decisions has been.