Led primarily by two former members of the Mexican special forces, Arturo Guzmán Decena and Heriberto Lazcano Lazcano, designated Z-1 and Z-3, respectively, the Zetas started as the military wing of the Gulf Cartel and became a fierce cartel, driven by military tactics and ruthless aggression.  This Episode explores how, despite their miliary elements, internal fractionalization and external threats arising from their merciless actions led to the rapid downfall of the once-feared cartel.  Today, Los Zetas are gone and all that remains are isolated factions and groups claiming, without much effect, to be its successors.