"In April 1945, the funeral train carrying the body of Franklin D. Roosevelt embarked on a three-day, thousand-mile odyssey through nine states before reaching the president's home where he was buried. It passed with darkened windows; few gave thought to what might be happening aboard. A closer look inside the train, however, would reveal a Soviet spy about to leak a state secret, a newly widowed Eleanor Roosevelt, who just found out that her husband's...