When the world was invaded by underground creatures that wanted to wipe out mankind from Earth, the post-apocalyptic survivors called The Day of Reckoning. Fifteen years later, people have the same signs indicating that a new attack is coming and they seek out shelter for protection. What will happen to mankind this time?

Armando Alvarez (Will Ferrell) has lived and worked on his father's ranch in Mexico his entire life. As the ranch encounters financial difficulties, Armando's younger brother Raul (Diego Luna), shows up with his new fiancé, Sonia (Genesis Rodriguez). It seems that Raul's success as an international businessman means the ranch's troubles are over as he pledges to settle all debts his father has incurred. But when Armando falls for Sonia, and Raul's business dealings turn out to be less than legit, all hell breaks loose as they find themselves in a war with Mexico's most feared drug lord, the mighty Onza (Gael Garcia Bernal).