She delves into the underworlds, all in an effort to inform the public.
"In a battle between fear and curiosity in my head, curiosity always wins," van Zeller said.
The award-winning journalist explores the inner workings of the global underworld's most dangerous black markets.
"The most challenging part of our work is to get people to actually talk to us," she said. "I'd say that for every yes we get, for every person that agrees to talk to us we get dozens, sometimes we get hundreds of no's."
In each episode, she journeys inside a different black market or trafficking network, from timely topics such as drugs and stolen cars to outlaw bikers and Amazon mafias, to meet the players, learn the business, and better understand the world's multitrillion-dollar shadow economy.
"Sometimes my team, we're just sad or shocked by what we just saw, but as journalists, our job is to inform and to seek information so that people can make the right choices and the right decisions," van Zeller said.
This week, she tackles white supremacy.
"You wouldn't necessarily think of it as a black market, but what we found in our reporting is that these people, these white supremacist organizations operate very much like a black market," van Zeller said. "But instead of putting drugs in people's bodies or guns in people's hands, they're putting hateful ideas in people's brains."
New episodes air Wednesday nights on National Geographic and stream later on Hulu.
People often ask what was the scariest moment I experienced while filming this season of TRAFFICKED. Spending time with American white supremacists openly pushing for a race war was just that. This week’s episode will haunt me for years. Watch tomorrow at 9/8c @natgeotv pic.twitter.com/AQU0OPKVmt— Mariana van Zeller (@MarianaVZ) January 5, 2022