In 1946, Master Sergeant Donald Nicholes was repairing jeeps on the sleepy island of Guam when he caught the eye of recruiters from the army's Counter Intelligence Corps. After just three months' training, he was sent to Korea, then a backwater beneath the radar of MacArthur's Pacific command. Though he lacked the pedigree of most U.S. spies - Nichols was a seventh-grade dropout - he quickly m…