Born in Iowa, schooled in science at Columbia University, and as American as baseball, George Koval was the ultimate secret agent. Because he had security clearances to the Manhattan Project, he was able to pass invaluable classified information that helped Soviet scientists produce an atomic bomb years earlier than US experts had expected. The FBI only identified him several years after he had returned to the Soviet Union, and in 2007, Vladimir Putin posthumously awarded him Russia's highest civilian honor for his contribution to the Soviet atomic bomb program.

As William J. Broad wrote in The New York Times, Koval was "one of the most important spies of the twentieth century," but because of his success he is also the least known. Sleeper Agent is his fascinating story, a real-life thriller as gripping as any spy novel and "worthy of John le Carre" (The New York Journal of Books).