After 1945 the former allies of the Second World War, the western powers and the Soviet Union, fought to impose their political systems and ideologies on Germany. In a divided Berlin, thousands of agents and spies from East and West fought the information war as closely and intensely as nowhere else. Former CIA agent Peter Sichel reports on the role of the intelligence agencies during the Soviet blockade of West Berlin and the airlift by the western Allies. Sichel was also involved in planning the spectacular tunnel built by the CIA to spy on the Soviet administration in East Berlin. A Russian intelligence expert reveals how the newly founded KGB tricked the Americans with the help of British double agent George Blake. The KGB also benefited from the cooperation provided by the powerful spy network of the East German state security, the Stasi. As a "man without a face", the head of Stasi foreign intelligence became a legendary figure. It took western intelligence decades to find out his name and identity: Markus Wolf. He helped the most famous East German spy, Günter Guillaume, to work his way up to the echelons of the West German government. Because the CIA was less efficient in classic espionage, the largest US intelligence agency, the NSA, installed a gigantic surveillance facility on West Berlin's Teufelsberg hill, in the process possibly gaining a decisive advantage in the Cold War, which came to an end with the fall of the Berlin Wall in 1989.