Intelligence historian Andrew previously wrote on the KGB with a prominent defector, Oleg Gordievsky. This time, his coauthor was the KGB's archivist from the early 1970s through the mid-1980s. A secret dissident, Mitrokhin took notes on the files that passed through his hands, and escaped to the West in the early 1990s with cartons of material that formed the basis of this book. The result of their collaboration is a dense but extraordinary work. The authors are coy about naming some Soviet spies in the West; others found themselves compromised by Mitrokhin some years ago. There are no huge surprises here; that the KGB plotted to sabotage Western power networks, routinely conducted assassinations through the early 1960s, and maniacally persecuted religious groups should not shock readers. But the weight of detail and the solid retelling of well-known stories, such as Soviet recruitment of British spies in the 1930s, make for a fascinating read. Among the more interesting conclusions is that much of the invaluable information dug up by Soviet spies never made it through the filters of paranoia, ideology, and sycophancy created by the Soviet leadership.