Mariana investigates fentanyl, a contributor to the deadliest drug crisis in U.S. history.

Mariana meets the craftsmen who make and sell the world's finest counterfeit U.S. dollars.

Mariana attempts to understand the vanity, insecurity and greed that drives steroid use.

Mariana sets out to understand the ugly business of illicit sex in America.

Mariana retraces one of the world's most intractable smuggling routes, following cocaine's path arou...

Mariana van Zeller tackles the black market for tigers and tiger parts, so secretive and dangerous t...

Mariana uncovers a supply chain of firearms being smuggled into the hands of drug cartels.