Documentary examining Operation Bernhard, the counterfeiting scheme devised by the Nazis during World War Two to undermine the British war effort. SS Intelligence employed a 104-strong workforce - consisting of Jewish prisoners in Sachsenhausen concentration camp near Berlin - to forge more than 3 billion Pounds, with the intention of flooding the UK with fake bank notes and so trigger huge inflation and destabilise the economy. Their best forgeries fooled the Bank of England, and the notes are considered among the most perfect counterfeits ever produced, being extremely difficult although not impossible to distinguish from the real thing. But instead of being dumped on Britain, the notes were eventually used to bankroll covert German operations, including the rescue of Mussolini. It is an extraordinary story in which life imitates a thriller. Four of the prisoners tell what happened to the cash they produced under threat of death, and how they themselves survived to tell their story.