Mariana retraces one of the world's most intractable smuggling routes, following cocaine's path from a remote Peruvian valley through Colombia's Caribbean coast, all the way to the streets of Miami. Despite the decades-long U.S. War on Drugs, cocaine production is at an all-time high, and Mariana meets some of the makers, smugglers, drivers and teenage backpackers who risk their lives to deliver America's favorite party drug.

Mariana uncovers a lethal supply chain of American firearms being smuggled into the hands of drug cartels and fueling record levels of gun violence in Mexico. A journey filled with jaw-dropping access to gunrunners, mules, cartel bosses and assassins takes an even more terrifying turn when the son of the world's most notorious drug lord, El Chapo Guzman, is arrested and the cartel that Mariana infiltrates decides to violently revolt.