With so few survivors of the Holocaust left to share their first-hand testimony, what is the right approach to those with accounts that cannot be proved? Ninety-three-year-old Denis Avey is a British hero of the Holocaust who helped save the life of an Auschwitz inmate. He wrote about this heroic act, verified by the man he saved, in a best-selling book. But its publication generated a heated debate. That's because Denis also claimed to have broken in to the Nazi concentration camp itself. Why would anyone do such a thing and was it even possible? Witness to Auschwitz examines the controversy surrounding this latest Holocaust account and asks why is it so important to know the truth?