Monsters is set in the city of Monstropolis where monsters reside and use the harnessed screams of the children of the human world to power their own habitat. At the Monster Inc. factory, “scarers” are tasked of scaring children and harnessing their screams through closet doors which serve as portals. Even though they frighten children, monsters think that children are dangerous and toxic to touch. The company faces the dilemma of the ever increasing number of children who don’t get scared. The movie focuses on the adventures of the two monster friends, James P. “Sulley” Sullivan who is top tanking scarer of Monster Inc. and Mike Wazowski who works as assistant to Sulley and rivals with the chameleon-like monster, Randall Boggs.
One day, someone accidentally brings a child inside the factory. Sulley discovers the little girl and hides her in his bag. Sulley then ambushes Mike on his date to ask for his help. At that moment, the little girl comes out and the Child Detection Agency (CDA) is called for assistance. Sulley and Mike escape with the little girl in tow. While at their home, Sulley becomes friends with girl and he starts calling her “Boo.” They return to the factory and try to deliver the girl back to her home using the portals. Randall also comes to the factory to who aims to kidnap the little girl. However, he manages to snatch Mike instead.
While being held captive, Randall tells Mike that he has built a Scream Extractor which can purportedly outdo the company’s current performance. Sulley comes to the rescue and saves Mike but turns out that Randall is connected with Waternoose, whom Sulley asks for help. Because of this, Sulley and Mike are exiled to the Himalayas where they meet a Yeti that leads them to nearby village which can take them back to the factory. Sulley goes back to the factory to save the girl while Mike goes some other way. While trying to save the girl, Mike comes and helps Sulley save the girl.
Inside the factory, the group ends up in corridors full of doors as they try to evade Randall. In turns out that Boo’s laughter can activate all of these doors which start a chase between Sulley’s group and Randall in between the human and monster world. At the end, they manage to trap Randall in the human world.
Afterwards, they set on finding the door that leads to Boo’s bedroom. When they find out that the CDA and Waternoose have sent Boo’s door to the Scarefloor, they try to confuse the CDA to get to the door. Waternoose then tells the truth to Sulley that it was his and Randall’s plan to save the factory by using the Scream Extractor to harness the screams from kidnapped children. At that moment, the CDA appears and arrests Waternoose. Sulley and Mike say their goodbyes to Boo before returning her home.
The movie ends with a newly innovated Monster Inc. which now work by making children laugh, a plan concocted by Sulley after his encounter with Boo. If you are looking for real scary monsters and not just cartoons check out this Horror Movie website.