the film begins when a monster named thaddeus unsuccessfully scares a child. one of the things he did wrong was that he left the door open, which is the worst mistake a monster can make because a child can walk out of the room and into the monsters inc. factory. according to mr. waternoose, the ceo of monsters inc., human children are toxic and even a single touch can kill a monster. for this reason, he needs scarers that are tough and frightening, such as sulley. sulley is the top scarer at the company, thanks to his assistant mike. randall, at second place, will work hard to take the top spot away from sulley.