Despite hundreds of books and thousands of articles on Jackie Kennedy, surprisingly little is known about her mother's role in her life and achievements. Often dismissed as a social climber who faded into the woodwork after she divorced Jackie's father-the dashing, disreputable "Black Jack" Bouvier-and married the rich Hugh D. Auchincloss, Janet not only played a pivotal part in Jackie's own wedding to JFK, but often served as a stand-in for Jackie...