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.