In 1943, a young official from the German foreign ministry contacted Allen Dulles, an OSS officer in Switzerland who would later head the Central Intelligence Agency. That man was Fritz Kolbe, who had decided to betray his country after years of opposing Nazism. While Dulles was skeptical, Kolbe's information was such that he eventually admitted, "No single diplomat abroad, of whatever rank, could have got his hands on so much information as did this...