At the end of the summer of 1859, twenty-two-year-old Peachy Quinn Harrison went on trial for murder in Springfield, Illinois. Abraham Lincoln, who had been involved in more than three thousand cases--including more than twenty-five murder trials--during his two-decades-long career, was hired to defend him. This was to be his last great case as a lawyer.What normally would have been a local case took on momentous meaning. Lincoln's debates with Senator...