Camera crews examine fentanyl's impact on addicts and how overwhelmed customs agents are striving to stop the flow. Also, a Boston dealer talks money.

A large shipment of cocaine is transported from rural Colombia to bustling Madrid. Smugglers beware: Police may be waiting to pounce.

As dealers and smugglers take advantage of addiction in Los Angeles, law enforcement agents search for drugs on both land and sea.

In the port city of Rotterdam in the Netherlands, cocaine kingpins employ fearsome hitmen to intimidate and silence suspected informers.

On the rough streets of Oakland, law enforcement searches for a mysterious RB rumored to be driven by a high-profile drug distributor.

Across cities and farms, meth addiction grips the state of Indiana, overwhelming cops and forcing countless residents to seek "refuge in oblivion."

As smugglers attempt to sneak drugs across the Caribbean, U.S. law enforcement agencies work to intercept the shipments before they reach land.

In America's Motor City, dealers cut corners to sell molly to the masses while police officers try to "think like the bad guys."

As violent street gangs attempt to squeeze out the old guard in Atlanta, a bounty hunter prowls for gang-connected dealers.

South of the border, drug traffickers use every trick in the book to push mass amounts of marijuana into the United States.

Addicts, dealers and law enforcement officials speak about Baltimore's transformation into "the heroin capital of America."

As Memorial Day weekend approaches in Chicago, cops strive to get weapons off the street while drug dealers prepare for an influx of buyers.