Even a reader not enamored of spy stories will have trouble putting this one down. Oleg Gordievsky was a true child of the KGB; his father and his brother were both dedicated lifelong officers. Gordievsky joined the international arm of the agency in the early 1960s, but he began to have doubts about the system he was serving. In 1973, while posted in Denmark, he was recruited by British intelligence. He would eventually rise to head the KGB operation in London. Over the years, he provided critical information to the West, bringing down Soviet spy operations in several European countries and in one instance alerting London and Washington to Moscow’s dangerous misreading of a NATO war game that could have led to nuclear disaster. The whole story, including Gordievsky’s return to Moscow, where, unbeknownst to him, he had been unmasked to the KGB by Aldrich Ames, their man in the cia, followed by his harrowing, made-for-Hollywood escape from the Soviet Union, unfolds with a pace and drama that recall the novels of John le Carré.