Many large cities lie in ruins, as well as the most recognizable and photogenic of monuments around the world, destroyed by a special-effects laden alien death ray. Someone who would never have been elected President in real life gives a rousing speech and leads the ragtag band of poorly-trained civilians in a grand battle against alien deathships whose size can only be described as "big ass". We win, of course, every damn time, because we are the civilization that invented 'Weekend at Bernie's'.