Inspired by Jesus's words on the cross, Bettany Hughes traces the history of this challenging virtue. What does it really ask of us? And how realistic is it to put into practice? She looks for forgiveness in the violence of the Crusades, the turmoil of the Reformation and the quest for peace in South Africa. At Ground Zero Bettany meets Cheryl McGuinness the widow of the co-pilot of the first plane to hit the Twin Towers, who in a remarkable gesture has chosen to forgive her husband's murderers. It is a paradox of history that the more secular the society, the more forgiveness flourishes.