When night falls, a different type of traveller crosses the border -- and cartel spotters are nearby watching. A truck driver's modified cab is carrying a secret commodity. Officers find a surprise in a car that has never crossed the border before.

An elite team prepares for the extradition of a cartel Sicario, or hit man wanted for murder in his home country; with the sale of guns and ammo strictly controlled in Mexico, cartels turn to America for the weapons to wage their wars.