For close to a century, a majestic chapter of American history has been buried in an obscure grave in Shelbyville, Tennessee. Beautiful Jim Key, the onetime ugly duckling of a scrub colt that became one of the most heralded and beloved heroes of his day, was famous neither for his beauty nor his speed but instead for his exceptional intelligence. Said to have an I.Q. equivalent to that of a human sixth-grader, Jim exploded on to the national scene...