See the underground world of drugs through the eyes of its makers. A former British gangster serves as guide into this illicit underworld, visiting a secret hash-making location nestled in the mountains. Check out growers in Holland who are leading a horticultural revolution in high-grade cannabis. Follow a batch of raw opium from an Afghan poppy field to an Iranian heroin lab. Follow the supply chain of cocaine through the eyes of Colombian peasant farmers producing the drug in a paste. (thetvdb.com)