Plot[ edit ] The city of Monstropolis in the monster world is powered by energy from the screams of human children. At the Monsters, Inc. It is considered dangerous work, as human children are believed to be toxic. Energy production is falling because children are becoming less easily scared, and Monsters, Inc. Waternoose, is determined to find a solution. One day, Sulley discovers that Randall has left a door activated on the scare floor and a little human girl has entered the factory.