The Auschwitz volunteer who uncovered Holocaust secrets

It was perhaps the bravest act of espionage of the Second World War. After voluntarily being imprisoned in the Auschwitz concentration camp for 2½ years, and smuggling out its darkest secrets to the Allies, Witold Pilecki overcame a guard and, with two comrades, escaped almost certain death.

http://www.timesonline.co.uk/tol/news/world/europe/article5891132.ece