Marijuana (S01E04)

Cannabis is the most widely used illicit drug on the planet. To many, it's an evil weed, but to some, it's a sacred herb, even a lifesaver. For decades the global supply was controlled by criminals, but now a quasi-legal industry worth billions of dollars is booming. Visit growers who are leading a horticultural revolution, hear from users consuming for medicinal purposes, go inside the "Green Rush" of medical marijuana in cities across the U.S. and the violent marijuana cartels in Mexico. (National Geographic)