Episode two goes to the world famous home of the Beatles, Liverpool - but we investigate the darker side. Using the port as the foundation for a criminal empire based on drug dealing, Scouse villains started to import cannabis, heroin and cocaine on an unprecedented scale. Exploring run-of-the-mill provincial crooks to some of the wealthiest gangsters in British history (including one with an entry in The Sunday Times Rich list); we chart the rise of the drug pioneers. Plus, find out how a supergrass helped bring down two of the country's biggest and richest criminals.

• Shaun Dooley