The endearing monsters of Monstropolis, a thriving urban center
whose primary energy source is children's screams, are running out of
power because kids are becoming increasingly harder to frighten.
Monstropolis's workers enter the kids' world via portals that lead to
Earth closets. Once there, they need to scare the kid and get out.
Monsters, you see, are terrified of children and must be
decontaminated if they bring back so much as a sock. Trouble arrives
when a little girl slips back into Monstropolis with them.