The new book by Gordon Corera, presenter of The Rest is Classified, is a story you won't want to stop reading. It is about Vasily Mitrokhin, who was first a disillusioned dissident and then a traitor of the KGB, stealing the most secret Soviet files and passing them to the West.

How do you steal a library? Not just any library, but the most secret and protected archive in the world. The answer is to be a librarian. Be so quiet that no one suspects what you are doing as you work secretly among the files. The work goes on for decades, but remains so low-key that even after your escape, with the help of MI6, no one even notices your absence.

The Spy in the Archive tells the unforgettable story of Vasily Mitrokhin – one of the archivists who loved nothing more than dusty files – who ultimately changed the world. As an internal editor of the KGB, the secrets he was exposed to within the walls of the KGB turned him first into a dissident and then into a spy, a traitor to his country but also determined to reveal the truth about the dark forces undermining Russia, forces that continue to operate in the country to this day.

Renowned author and historian Gordon Corera recounts for the first time the operation of smuggling this valuable asset out of Russia. It is a breathtaking thriller with vivid flashbacks to Mitrokhin's former life as a KGB idealist, ready to do whatever he could to serve the Soviet Union, and the slowly growing realization that the communist state was holding its own people captive. It is the story of what it meant to live in the Soviet Union, to raise a family, and then the journey of a man from the heart of the Soviet state to disillusionment, betrayal, and escape. At its core is Mitrokhin's determination to confront the most powerful institution in the world by revealing its darkest secrets. This is the best non-fiction narrative.