In his book, Andrew Roberts - winner of the Wolfson History Prize (the historians' Booker) - explores the secrets of leadership of two of the four men who comprise this ground-breaking TV series - key men of twentieth century history - Adolf Hitler, Winston Churchill, John F Kennedy and Martin Luther King. Each had a distinctive leadership style, each achieved greatness. Hitler - fresh insights into how he instilled loyalty. Churchill - far more ruthless with his staff than Hitler, but far more willing to listen and accept advice. Kennedy could rely on his family's fortune when he stood to be elected as the US's youngest president. Martin Luther King, whose help give the black Americans their rights so long denied them. Given that two of the four leaders were assassinated, one committed suicide and only one survived into benign old age, Andrew Roberts also examines the risks of leadership