On the night of President Abraham Lincoln’s assassination, his frantic wife, Mary, calls for her best friend and confidante, Elizabeth Keckley. But the woman is mistakenly kept from her side by guards who were unaware of Mary Todd Lincoln’s close friendship with the black seamstress.      With vivid detail and emotional power, Ann Rinaldi delves into the childhoods of two fascinating women who became devoted friends amid the turbulent times of the Lincoln administration.     Includes an author’s note, a reader’s guide, and a bibliography.