The story of Adolf Tolkachev, the United States' most successful and valuable agent in the USSR, is a story from the Cold War era. Engineer and designer Tolkachev was not a member of the CPSU, did not serve in the army or special services. He did not seek to enrich himself and did not want to leave the country. He had never been abroad and knew almost nothing about the United States. Tolkachev himself offered his services to the Central Intelligence Agency and, over several years of espionage activity, handed over thousands of pages of highly valuable secret documentation to the United States. His exposure was not the result of a mistake by the Moscow station or a cunning KGB operation - he was betrayed by a former CIA officer.