A mother and son find themselves faced with a brutal alien invasion where survival will depend on discovering the unthinkable truth about the enemy.

A group of young mice is in the ruins of a church, practicing singing for an upcoming service. After singing an adulterated version of "Hark! The Herald Angels Sing," the mice wonder about the last line, "Good will to men." One of them asks the choirmaster, an old mouse, "What are men?" The old mouse explains that they all killed each other off by building bigger and more destructive weapons, first guns, then missiles, then bombs.