The title is somewhat misleading, since this book is a fairly complete study of the history and technique of espionage, rather than a prophetic picture of the future. It is rich in dramatic narrative of the exploits of famous spies, much of the material has been amply vouched for, a good deal is hearsay and legend. Diagrams and illustrations of secret ciphers, concealed plans of fortifications, various forms of spy communications land added interest. Rather sensational. Frankly pessimistic about the future. A book of undoubted interest to anyone interested in world affairs as well as to those intrigued by the always glamorous subject of spies.