In a parallel world, monsters of all kinds rely on electrical power harnessed from the screams of human children. This kind of power can be difficult to produce however, as many children are no longer scared of monsters. Nevertheless, the brave monsters at Monsters, Inc. put their lives on the line to harvest screams. The company's top scarer, James Patrick "Sulley" Sullivan, and his long-time friend, Michael "Mike" Wazowski, are proud to produce the most scream energy for Monstropolis.

But even as a top employee, trouble finds its way to Sulley. A small human girl has infiltrated the company building after hours, plunging Monstropolis into chaos. Sulley and Mike are forced to hide the girl until they can send her back home, or risk facing dire consequences. As the pair spend more time with "Boo"—as Sulley has now named her, their existing notions about humans slowly begin to crumble.

[Written by MAL Rewrite]