A look at the complex inner-workings of the global underworld, black and informal markets.

Mariana goes in search of the elusive chemists who make the world's LSD.

Mariana exposes the dangers of the growing and deadly ghost guns industry.

Mariana investigates how illicit oil is fueling terrorist groups worldwide.

An alarming message from her son's middle school about MDMA sparks van Zeller into high gear. She traces the supply chain of "the love drug" within the Los Angeles clubs back to its booming epicenter in the Netherlands, where a mob-infested underworld has recently murdered a well-known journalist.

Mariana explores surrogacy's dark side; a babies-for-cash black market.

Mariana investigates the lucrative black market for private data.

Mariana embeds with crypto scammers who show her how they make millions.

Mariana investigates the growing popularity of bare-knuckle fighting.