The book by a prominent historian and archaeologist is dedicated to the legendary library of Ivan the Terrible, the history of which the scientist studied for more than 40 years. In the early 30s, he conducted search work in the dungeons of the Moscow Kremlin, which was stopped after the murder of S. M. Kirov. The first volume traces the history of the library, talks about the unique books stored in it, the second describes the initial stage of its search by Stelletsky. The absence of the third volume, which mysteriously disappeared, is in a certain sense made up for by the author's diaries, which read like an adventure novel. Intended for the general reader.