You have a filing cabinet, a midsize sedan, and six pairs of slacks: to the outside world you are a verified adult - so why is it your first choice for movie night is always a Pixar? Who knows. Just watch.
In order to power the city, monsters have to scare children so that they scream. However, the children are toxic to the monsters, and after a child gets through, two monsters realize things may not be what they think.