Tres Caínes' tells the incredible true story of the Castaño brothers: Carlos, Fidel and Vicente, who shook the history of Colombia in their quest for justice and revenge. The Castaño brothers suffered a family tragedy at the hands of the guerrillas and vowed not to rest until they had brought down those responsible. They created a powerful private army financed by landowners, politicians, military and drug traffickers to wipe out the guerrillas, but in the end, they ended up dragging an entire nation into a war that killed even their own family.