As Nelson Mandela prepares to step down as president of South Africa, FRONTLINE presents a deeply personal biography of one of the great figures of the 20th century. "The Long Walk of Nelson Mandela" tells the story of the man behind the myth, probing Mandela's character, leadership and life's method through intimate recollections with friends, political allies, adversaries, and his fellow prisoners and jailers on Robben Island where Mandela spent 18 of his 27 prison years. It's a two-hour biography filled with insights: from Mandela's 'royal' upbringing in the rural Transkei where old chiefs still remember him as a young boy and where his values and attitudes were shaped by tradition and royal prerogative--to old colleagues' anecdotes about his self-discipline, guarded privacy and quite early sense of his own historic destiny. A major part of "The Long Walk of Nelson Mandela" probes how Mandela transformed himself in prison from an impetuous, risk-taking radical into a mature leader and statesman. On Robben Island he became the master of his own prison; through intelligence, charm and dignified defiance he bent to his will even the most brutal prison officials. And from this he took a great lesson, says Richard Stengel, co-author of his memoirs: "He realized that the relationship between him and his Afrikaans guards was a microcosm for the whole South African experience. If he could somehow come to some modus vivendi with his guards, then he could maybe bring South Africa to the promised land. "