Stalin, like no other leader, understood and appreciated Soviet intelligence, which by the beginning of the 30s had become the best in the world. It was thanks to military intelligence that it was possible to prevent an attack on the USSR in 1927 and 1929-1932. It was based on intelligence that Stalin was able to prove to his comrades-in-arms the need for industrialization, which ultimately predetermined the outcome of the Great Patriotic War. It was the GRU, which outplayed the intelligence of the III Reich in all respects, that provided Stalin with overwhelming information superiority over Hitler. The new book by the leading historian of the special services, entirely based on previously unknown archival documents, for the first time sheds light on the most secret episodes of the secret war, allowing you to look behind the scenes of big politics, into the holy of holies of the GRU - what military intelligence reported to Stalin, how he reacted to this data, what conclusions he made and what measures to strengthen the country's defense capability he took.