Mariana van Zeller takes viewers inside the world’s dark corners and criminal underbellies in “Trafficked,” her new National Geographic docuseries.

Airing Wednesdays at 9 p.m., “Trafficked” takes a deep dive into various underground industries around the globe, including episodes exploring the world of fentanyl smuggling in Mexico, scamming in Jamaica and counterfeit money in Peru. 

The Portuguese-born van Zeller, 44, is a Peabody Award-winning investigative journalist and correspondent for National Geographic and Fusion. Her previous documentaries include  “This (Illegal) American Life,” “Soccer’s Lost Boys” and “El Chapo: CEO of Crime.”

Van Zeller answered some questions for The Post about “Trafficked.” 

How did this show come about?

I’ve been covering the underworld and these black markets for over 15 years. And one thing that I started realizing is that there’s so much information out there about the formal economy. There are TV stations and radio channels and magazines devoted to analyzing and studying every twist and turn. But we know so little about the informal economy; the black markets that make up almost half of the global economy. So I felt we had a unique opportunity here with this show to shine a light into these worlds and [to] understand how the power structures work. 

Did you learn anything that surprised you?

Oh, so much.  We think about black markets as happening in these faraway places and hidden locations. But actually what this show will tell you is [that] they’re all around us. And they often happen in plain sight. We filmed some of the season just a couple of miles from my house in LA. We saw a gun deal going down with a car being packed with AK-47s to leave that night for Mexico. I spent time with pimps and sex traffickers just a few miles from my house. 

Was it hard to get people to agree to talk or appear on camera? 

For every “yes” that we get, there’s dozens and dozens of “no’s.” When we arrived in Peru to do the episode on counterfeiting, I had my whole team in place and we’d spent months preparing for this moment. So we went and met with this family of counterfeiters that run a huge operation in Lima, where 60 percent of fake US dollars come from … And they said, “Tomorrow we’re going to give you access into this world.” And then the next day we showed up and waited for hours and they never came. So we had to start from scratch and go back to the US. Because we end up showing the access onscreen, you might think that it was easy or that everybody said “yes.” But it’s not the case. It was incredibly hard to get people to actually talk to us. 

Did you ever feel nervous or unsafe? 

There were plenty of times. We minimize the risk as much as possible, but there are moments where things don’t go as planned. There was one situation in Mexico where we were going to a region controlled by the Sinaloa Cartel. We were walking into this forest area with these gunmen, and they told us, “While you’re with us you’re protected, but if … there’s a firefight, you’ll be stuck in the middle of it.”

You’ve spent a lot of your career on these subjects. Why do you think they’re important to cover? 

I’m fascinated by the people who work in these worlds — traffickers, smugglers, black market operators. I hope what people take away from this show is not that we live in a very dangerous and depressing world. Yes, depressing and dangerous things are happening around us, but there is common ground between even people that we think are the most different from us. If we sit down and listen to their stories, there’s a whole lot that we can learn from the decisions that they’ve made. It’s a great conversation starter for ourselves about the opportunities that we were given in life. I truly don’t think anyone is born wanting to be an outlaw or a criminal, but if you give them a chance to explain how they started operating, only then are you able to address the root causes of black markets around the world.