A comprehensive history of the world's intelligence services during the interwar period and during the Second World War. The evolution of intelligence, counterintelligence and cryptanalytic bodies of various states of the world is explored, their structures, personalities, and operations are described. It is replete with exclusive material, in particular, on the intelligence services of France, Switzerland, Sweden, Poland, Czechoslovakia, China, Japan, Canada, Romania, Holland, Portugal, the Vatican, and Latin American republics. Much space is devoted to domestic operational bodies. The book was written using numerous sources, including archival materials. Most of the information was never made public in Russian, and some of it did not appear in the open press abroad. It can serve as a full-fledged encyclopedic-level textbook on the history of intelligence services and, at the same time, is of interest to a general reader interested in the history of the 20th century.