Law enforcement uses informants to stem the trade in drugs in St. Paul and Minneapolis. The cities are home to some of the purest heroin in the country. Drug dealers use vehicles to stay mobile.

After a rebrand as Molly, MDMA is experiencing an explosion in popularity. Marketed as a purer form of the drug used in ecstasy, suppliers are struggling to keep up with growing demand.

Mexican cartels use Dallas as a control centre for the drug trade. Local dealers can take advantage of the city's role on the southwest border of the U.S. as a gateway for drugs and get rich.

Baltimore has one of the biggest heroin problems in the United States. Officials try to cope as the heroin market expands into the suburbs. Many of those now addicted to drugs lose their jobs as the city's steel mills close.

The city is being flooded with narcotics. Puerto Rican dealers are used as middlemen by Dominican drug networks tied to a Mexican cartel. All communities are touched by the epidemic.

Dealers compete to deliver drugs to those on Wall Street. Drugs are used by brokers and traders to keep them performing at work. Becoming an epidemic, police are fighting to disrupt the trade regarded as Wall Street's dirty little secret.

Drugs are interwoven with the hip-hop industry. Artists play up their ties to the drug business but law enforcement cracks down on the use of the music as a cover for the trade in drugs.

The changing opinions on drugs in the porn industry. The tolerance of drugs on set is shrinking as the industry reacts to HIV scares. Cocaine and meth use is popular in the changing environment.

The students heading to Cancun and its closeness to South America make for a lucrative market. Police try to keep tourists safe as cartels battle for control with independent dealers.

Drugs find their way into two jails in the face of tough drug policies. Meth is the drug of choice in California while in New Jersey heroin is king. Officers and inmates battle for control.

The Domincan Cartel brings massive quantities of cocaine into New York. Continuous supplies are needed to meet demand. A drug boss explains how Dominican Republic smuggling has become big business.