Top Scarer Sulley (voiced by John Goodman) and his enthusiastic Scare Assistant Mike (voiced by Billy Crystal) work at Monsters, Inc., the largest scream processing factory in Monstropolis. The main power source of the monster world is the collected screams of human children. Monsters believe children are dangerous and toxic, however, and they are scared silly when a little girl wanders into their world. Sulley and Mike do their best to return the girl home, but they face monstrous intrigue and some hilarious misadventures along the way.