Leading up to the US entry into WWII, Germany set up a sophisticated and productive espionage ring, which effectively utilized well-placed German Americans in the States. They were able to infiltrate key military and industrial facilities, and succeeded in obtaining critical information, including plans for the exceptionally accurate and very secret Norden bombsite device. When naturalized American William Sebold visited his native Germany in 1939, German intelligence officers saw him as a prime target for recruitment. Threatened with arrest, Sebold seemingly agreed to work for the Germans, but they woefully misjudged him. Returning to New York, he contacted the FBI and told all. In his new book Double Agent, journalist Peter Duffy uncovers how Sebold became the center of a 16-month investigation that led to the arrest of 33 enemy agents in June 1941. Known as the Duquesne Spy Ring, the colorful cast of traitors included military contractors, a South African adventurer with an exotic accent and a monocle, and even a Jewish femme fatale.