Windy City High (S04E03)

Chicago, one of the biggest open-air crack and heroin markets in America, is at saturation point. It's an addict's dream as dealers compete with high purity drugs sold in very affordable quantities. The result: record levels of overdoses and homicides as gangs fight over drug turf. Go inside the deeply entrenched and violent world of the city's drug-corner industry. (National Geographic)