The entire vast modern American intelligence system—the amalgam of three-letter spy services of many stripes—can be traced back to the dire straits that Britain faced at the end of June 1940. Before World War II, the US had no organization to recruit spies and steal secrets or launch secret campaigns against enemies overseas. It was only through Winston Churchill’s determination to mobilize the US to help in their fight against Hitler that the first American spy service was born, one that was built by scratch in the background of WWII. In Need to Know, former CIA analyst and trained historian Nicholas Reynolds explores the birth, infancy, and adolescence of modern American intelligence. In this first definitive account, Reynolds combines little-known history and gripping spy stories to analyze the American codebreakers’ and spies’ origins and contributions to Allied victory, revealing how they laid the foundation for the Cold War—and all other conflicts to come.