Transcript for Inside the Sinaloa Cartel’s fentanyl pipeline
Reporter: Five years ago, almost no one had heard of it. Today, it's a household name. Fentanyl. Reporter: In the U.S., fentanyl is helping drive overdose deaths to record highs. It's wiping out a generation. Reporter: While in Mexico, it's disrupting the drug trade in ways not seen in generations. But few people understand how the cartels are getting their hands on the chemicals necessary to make fentanyl or what the fallout will be if they continue to churn these raw ingredients into deadly pills and powders. Reporter: From Mexico's cartel country to the border and into American communities, I'm going deep inside the fentanyl pipeline to see exactly how it's fueling the most devastating drug epidemic in U.S. History. Reporter: In just a few years, fentanyl has become the most popular synthetic opioid on the sts. And Mexico's cartels have stepped up to supply this demand. But it's a little-known secret that the cartels can't make the drug themselves. They first need to source these potent chemicals from somewhere or someone else. They're saying it was one of these big cargo ships we see all around us that threw the barrels overseas, then the fishing boat here got a gps location of where to pick them up, brings them out, then there's a meeting point where these guys pick it up and take it off to land. Reporter: In 2015, fentanyl emerged on the black market in a big way. Potent, cheap, and readily available on the streets without a prescription. In the U.S., overdose rates exploded to record highs. But here in Mexico, fentanyl became a boon to the underworld economy. Which is why I've journeyed inland to witness how the cartels transform the precursor chemicals into street-ready drugs. It's happening tonight in an underground lab where we'll get a glimpse into the future of the Mexican drug trade. Reporter: Unlike heroin, cocaine, or marijuana, fentanyl doesn't nee farmland or water sunshine. It can all be made in an underworld lab like this, by a handful of cartel chemists. They're saying just did this little amount here, if you were to ingest this, this amount could kill you immediately, that's how powerful this stuff is. Everybody, we should put T masks on. This is where it starts getting dangerous here. Reporter: If these chemists combine the raw materials just right, in a matter of hours, they'll have successfully completed the next step in the process, creating sellable black market fentanyl. This is the pure fentanyl. They mixed all the liquids that come from Asia, a lot of times from China. They mix and it they make this. Reporter: I'm starting to think my team and I should get the hell out of here. Outlaw narco chemists accidentally kill themselves all the time. Once the paste dries and the room clears of deadly fumes, I'm told it's okay to take off our masks. Now that the chemical ingredients are properly balanced, it's time to craft the fake m-30 pills, each one designed to mimic the look of oxycontin, the most popular pain Kilner America. The ugly truth is that fentanyl supports an incredibly lucrative underworld economy. That means jobs for cartel accountants, couriers, and chemists. And for those who undertake one of the most dangerous roles in the pipelines, prepping the drugs for the final crossing into the United States. I'm watching a shadowy game of cat and mouse. In less than an hour, these drugs are headed to the most frequently crossed and one of the most heavily patrolled borders in the world. Last year, U.S. Customs and border protection seized more than a ton of fentanyl. And yet these packers plan on foiling thousands of highly trained agents and billions of dollars of surveillance technology with little more than homemade ingenuity. He has other products here. He has mustard. He has softener, laundry softener. All this is to avoid any sort of smell. Reporter: The packers tell me they'll make $2,000 for their work tonight. $400 per package. And just like everyone I've met on this journey, they do their job, then they pass the drugs on to the next link in the supply chain. The girl he's referring to is tonight's driver. In the trafficking world, she's called a drug mule. But I'll call her Beatrice. Reporter: Beatrice tells me she's been doing this for a year and makes $3,000 per crossing. Fentanyl trafficking convictions in the U.S. Have increased by nearly 5,000% over the past six years. And those who are caught are almost always sentenced to prison. She has to be super nervous, she's packing five kilos of fentanyl. So it's a very strange feeling because on the one hand, we've met her, and don't want her to get caught, and I'm actually nervous for her. But on the other hand, she has a car packed with drugs that can kill a lot of people in the U.S. It's complicated. I know Beatrice has a growing family to provide for. But in all my years reporting on the opioid crisis, it's the parents who lost sons and daughters to overdoses that I remember the most. And I can't help but wonder what they might think as I watch Beatrice attempt to carry a deadly shipment across the border. But this is how a majority of drugs are smuggled into the U.S., according to the Dea. Through legal ports of entry on E southwest border, stashed inpassenger vehicles or tractor-trailers. And I'm here to witness it for myself. She's stopped, she's being checked right now. Just put the cameras down. Just when I'm certain she's busted -- they're letting her yeah, she's just going into her car and leaving. I can't believe it. They just let her go, I can't believe it. When we contacted cpv for comment they told us, U.S. Customs and border protection seized over 750,000 pounds of illegal narcotics in 2019. Our officers remain relentless and are always working to stay on ahead of the cartels. But with so much demand for drugs, so much money to be made, it's a difficult task. In recent years, there have been almost 200 drug overdose deaths in the U.S. Every single day. And fentanyl is the major reason. I think that's actually our woman. With the drugs inside her car. There's a guy in an Orange jumpsuit with a mask. So looks like that's where they're doing the deal, right here, out in the open. Reporter: The masked men tell me they're all native angelinos, American citizens who work directly for the sinloa cartel. Do you know what's in the packages? I don't know. Can you tell me more or less where they're heading? This is one of the main thoroughfares we have here. Like a hot potato where they want to get it out as soon as possible. Reporter: Never have so many people been addicted to such a deadly narcotic. Never has the need for solutions been more urgent. I worry that the fentanyl supply chain seems too big to fail. Too many people benefit. Americans will have to find a way to slow the demand. Because the suppliers will always find a faster and more profitable way to deliver the goods. New episodes of "Trafficked," an eight-part docuseries, airs Wednesday evenings on national geographic.
This transcript has been automatically generated and may not be 100% accurate.