At the height of the Cold War, a seemingly unassuming Soviet electronics engineer reached out to several Americans he encountered in Moscow and offered his services. While he was initially ignored, the engineer, Adolf Tolkachev was eventually accepted by the CIA’s Moscow station as a volunteer spy for the United States. Over a number of years, and under the nose of the ever-watchful KGB, Tolkachev passed on highly classified information about Soviet military technology to U.S. intelligence operatives. The documents he shared were of immense strategic value at a time when tensions between the two superpowers were at their peak.