This book grew out of my personal experiences living in divided Berlin during the mid-1980s. I was not a spy, but rather a Wall-hopper, student, and observer. Although I had read several John le Carré and Len Deighton novels that took place in the spy capital, Berlin, and even knew one of the Cold War's most celebrated spies – Adolf Henning Frucht, a Central Intelligence Agency (CIA) spy who was caught by the Stasi and then traded ten years later at the famous spy bridge, the Glienicke Brücke – I had no special interest in the subject. After returning to Berlin on the eve of unification in 1990 and witnessing the constant fire of revelations about the East German secret police, I could not believe all the secret activity that had taken place behind the scenes of the drab and banal black-and-white world I had experienced in communist East Berlin.

The first layer of secrecy I began to peel away at in a professional capacity was the history of science in East Germany. That quickly led to research on espionage and technology transfer and to a mysterious defector.