See the world that would create a place like Gotham City and the people who put on masks to protect it. 1919-1939 was a time of unprecedented change, from the 'war to end all wars' to the crash of the stock market, from the enforcement of prohibition to the rise of the celebrity gangster. This documentary series collects the years of research following the Dark Knight and the colourful characters that would dominate the headlines for a short period.