The history of espionage in WWII remains an intellectual challenge. Records were lost or destroyed. Operations were planned and executed with a degree of informality unthinkable in our more bureaucratized era. Lines of loyalty were often blurred. Waller, a former CIA and Foreign Service official, synthesizes extensive research in British archives with a broad spectrum of published sources in a volume that focuses on the human dimensions of espionage and conspiracy. Among its outstanding points is Waller's strong case that a coup against Hitler in the late 1930s might have succeeded with Anglo-French support. The author also convincingly demonstrates that the British did not withhold information on Operation Barbarossa to protect the Ultra secret or force Russia into the war. Waller's sympathy for the moral dilemmas confronting German Abwehr chief Wilhelm Canaris and his admiration for the skill and daring of Allen Dulles of the OSS are controversial but defensible. This is a useful and stimulating contribution to the study of the shadow war from 1933 to 1945.