In 1940 the Polish resistance decided it needed to send an agent to Auschwitz concentration camp. They were desperate to find out what was going on in a place that even by that stage of the war had an evil reputation. Historian Jack Fairweather tells the story of Witold Pilecki the Pole who volunteered for the job. He smuggled out first accounts of the camp to the rest of the world. He chronicled its transition from a concentration camp for Polish political opponents to a factory of genocide.