"In the mid-1970s, the CIA and KGB watched Karel Koecher closely--they were both convinced he was working for the enemy. And they were both right. Traveling with his wife, Hana, Koecher posed as a Czechoslovak asylum seeker and arrived in the US as a Communist sleeper agent. After parlaying a doctorate from Columbia into a job at the CIA, Koecher proceeded to operate as a double agent at the height of the Cold War. Using newly declassified documents,...