Plot: To celebrate its 50th anniversary in May 2011, this probing documentary brings together an extraordinary cast of interviewees, from Sting to former home secretary Jack Straw, to shed light on how, as a 'letter-writing organisation, Amnesty International has changed the world and how the world has changed Amnesty International. It poses the fundamental question: has the human rights movement been able to hold back mankind's capacity for atrocity? Part of BBC4's Justice season