Picking his way through the Soviet archives that Boris Yeltsin had just thrown open, in 1991 Tim Sebastian, a reporter for the London Times, came across an arresting memorandum. Composed in 1983 by Victor Chebrikov, the top man at the KGB, the memorandum was addressed to Yuri Andropov, the top man in the entire USSR. The subject: Sen. Edward Kennedy. "On 9-10 May of this year," the May 14 memorandum explained, "Sen. Edward Kennedy's close friend and trusted confidant [John] Tunney was in Moscow." (Tunney was Kennedy's law school roommate and a former Democratic senator from California.) "The senator charged...