While Oleg V. Penkovsky may not, literally, have saved the world, this tellingly detailed saga reconfirms that the turncoat GRU colonel provided the West with priceless intelligence during the early 1960's, when the cold war very nearly turned hot. Drawing on hitherto unavailable transcripts of Penkovsky's debriefings by the CIA and the UK's MI6, Schecter (coauthor, Back in the U.S.S.R., etc.) and former KGB officer Deriabin (The KGB, 1989, etc.) deliver a fascinating rundown on a defector in place who wreaked incalculable havoc on the Soviet regime. With his own military career stalled by dint of a White Russian father who had fought the Bolsheviks, Penkovsky offered himself to the West as a ""soldier of freedom."" Eventually accepted as a genuine apostate, he proved an astonishingly fertile source of accurate data on the USSR's nuclear capabilities, geopolitical aspirations, industrial priorities, and allied matters. Under his cover as a trade official, the GRU operative often traveled to London, Paris, and other points beyond the Socialist Bloc to talk with his Western contacts; otherwise, the high-ranking mole was obliged to pass on his espionage material (including exposed microfilm) at dead drops or embassy receptions in Moscow. Penkovsky's information proved invaluable to JFK in his confrontations with Khrushchev prior to the Berlin Wall, as well as during the Cuban missile crisis. In the meantime, however, Penkovsky took one risk too many and was arrested by the KGB and, following a show trial, executed in 1965. Having evaluated the theories advanced to explain Penkovsky's apprehension, the authors conclude that the truth won't be known until Kremlin files are opened. They leave little doubt, though, that their philandering, money-minded subject would probably have remained a loyal apparatchik had not his patrimony precluded his promotion to general. A fascinating portrait of a double agent whose active disaffection with the communist system helped consign it to history's dustbin.