The compulsively readable new book from The Rest is Classified host Gordon Corera. About how one man – Vasili Mitrokhin – turned first disaffected dissident and then traitor to the KGB, stealing the most secret Soviet archives and smuggling them to the West.

How do you steal a library? Not just any library but the most secret, heavily guarded archive in the world. The answer is to be a librarian. To be so quiet, that no-one knows what you are up to as you toil undercover and deep amongst the files. The work goes on for decades but remains so low key, that even after your escape, aided by MI6, no-one even notices you are gone.

The Spy in the Archive tells the remarkable story of how Vasili Mitrokhin – an introverted archivist who loved nothing more than dusty files – ended up changing the world. As the in-house archivist for the KGB, the secrets he was exposed to inside its walls turned him first into a dissident and then a spy, a traitor to his country but a man determined to expose the truth about the dark forces that had subverted Russia, forces still at work in the country today.

Bestselling writer and historian Gordon Corera tells of the operation to extract this prized asset from Russia for the first time. It is an edge-of-the-seat thriller, with vivid flashbacks to Mitrokhin’s earlier time as a KGB idealist prepared to do what it took to serve the Soviet Union and his growing realisation that the communist state was imprisoning its own people. It is the story of what it was like to live in the Soviet Union, to raise a family and then of one man’s journey from the heart of the Soviet state to disillusion, betrayal and defection. At its heart is Mitrokhin’s determination to take on the most powerful institution in the world by revealing its darkest secrets. This is narrative non-fiction at its absolute best.