It’s amazing to think that a city could run on the noise kids make when they scream, and predictably, there's a business built around creating scary creatures specifically to elicit those sounds. When a security problem arises and toddlers take over the monster factory, their manager, "Waternoose," worries about the impact on his company. The job of getting all these little ones back home falls to the pest control team. Naturally, one girl named “Boo” escapes and quickly becomes friends with the large, fluffy "Sully." Though he has a frightening roar, he’s not as intimidating as he seems, and alongside his one-eyed green friend "Mike," they embark on numerous entertaining escapades to protect her from the unpleasant "Randall" and return her home. The plot is straightforward, but it's effective. The animation is pleasant to look at, the writing moves along briskly with some clever observations, and the characters—particularly “Sully”—are imaginatively developed and captivating. Thankfully, the screaming children aren’t overwhelming, resulting in something akin to a love story. It incorporates familiar Pixar/Disney themes of loyalty and cooperation, but presented with a greater sense of fun, even featuring a yeti who always has snow-cones available!

Source on TMDB