During the Cold War, superpowers amassed nuclear arsenals containing the explosive power of one million Hiroshimas. The Soviet Union secretly plotted to create the "Dead Hand," a system designed to launch an automatic retaliatory nuclear strike on the United States, and developed a fearsome biological warfare machine. President Ronald Reagan, hoping to awe the Soviets into submission, pushed hard for the creation of space-based missile defenses. This, the first full account of how the arms race finally ended, provides an unprecedented look at the inner motives and secret decisions of each side.