Follow DEA agents on their quest to track down and bust narco-submarines in one of the most violent regions of Colombia- the coastal town of Tumaco. NGC joins the investigation, taking to the streets and swamps with armed marine patrols. We'll meet a drug sub informant who ventures out to mark a sub site for capture- and subsequently goes missing. And meet one of the very first drug sub inventors, now "in hiding" as he shows original "test" footage of his creation. We'll also examine several seized semisubs for clues to their makers. And our cameras are there for a first-time look inside the biggest prey of all- a fully submersible cocaine sub!