Max Hastings' book is certainly not an exhaustive account of the secret warfare in World War II. The author focused on a concrete approximation of the means used by both sides in this secret war and the figures who influenced them. It is unlikely that more facts will be revealed - perhaps if Vladimir Putin published the Soviet archives... Most of the published works focus on the intelligence activities of that country. In this book, the author decided to examine the issue of intelligence activity on a global scale. Numerous books on World War II intelligence focus on what spies (or codebreakers) accomplished, but what matters is the extent to which the secret information obtained changed the course of events. Soviet espionage was far greater in scale than that of any other belligerent and provided the Russians with extremely valuable technical information originating from Britain and the United States, but Stalin's paranoia crippled the use of the enemy's secret political and military materials. Max Hastings' book is excellently elaborated and, above all, historically based and accurate. Although it describes many events in great detail, it is readable and (against the background of the tragic events of the Second World War) there is also humor in it.