Whittaker Chambers and Elizabeth Bentley shocked America in 1948 with their allegations that Communist spies had penetrated the American government. The resulting perjury trial of Alger Hiss is already legendary, but Chambers and Bentley also named Harry Dexter White, a high-ranking Treasury official. (Hiss himself thought that White had been the real target of the House Un-American Activities Committee.) When White died only a week after his bold defense before Congress, much speculation remained about the cause of his death and the truth of the charges made against him. Armed with a wealth...