MS-13 is a gang so deadly and violent that the Trump administration tried to officially label them a terrorist group. But how does this gang really operate? How do they fit into the drug trade which is transforming Central American countries into narco-states? How have they virtually taken over entire cities? This is how America gets MS-13 totally wrong – totally misunderstanding what this gang is and how they actually work. We go inside El Salvador's deadliest street gang.