San Antonio, Texas. The bodies of various drug cartel members are turning up mangled and drained of blood. Tough DEA agent Carlos Seguin discovers that the grisly murders are being committed by a pack of chupacabras, which are lethal predatory creatures of local legend. Carlos, his feisty new partner Tracy Taylor, wayward estranged son Tommy, and several others make a desperate last stand against the bloodthirsty beasts at the famous fort The Alamo.