The arms race between the Soviet Union and the USA was the most dangerous confrontation in the history of the world. Soviet leader Nikita Khrushchev's decision to place nuclear missiles in Cuba, and US President John F. Kennedy's willingness to call his bluff, brought the Soviet Union and the West to the edge of a cataclysmic nuclear war. Now, on the fiftieth anniversary of the Cuban Missile Crisis, Robert Holmes, a British diplomat in Moscow during the early 1960s, provides an answer to one of the greatest mysteries of the Cold War. Kennedy's confidence in his brinkmanship hung on the evidence provided by Oleg Penkovsky, the MI6CIA agent inside Soviet military intelligence.