The hero, Paul Perez, is a trouble maker who often spends his days pranking or harassing others. But of course, he was always punished for his childish antics. His latest being how he taught his pet parrot to say "Don't do your work, the teacher is a jerk,". But this is not enough to get him expelled, only sent to the principal's office. He accidentally trips the teacher however and she gets hurt!
And so, Paul soon finds himself being shipped off to a boarding academy for overachievers called "The Caring Academy". Paul really is not an overachiever, but his father pulled some strings to get him in. Paul's new roommate Brad is a violinist practicing for one of the Stradivarius acts at the upcoming school-wide talent show and he is warned to get a talent before the show. After Paul's parents leave, he meets two girls named Celeste and Molly. Both of them warn him to leave as soon as he can. Paul thinks it is a big joke and starts clowning around before class starts. But he learns the hard way when a giant grotesque monster enters the room and licks his arm with her enormous cow tongue!
It turns out that Paul's teacher Mrs. Maaargh really is a giant monster. Mrs. Maaargh and her students explain how she is a big booster on Darwinism and survival of the fittest. She then expressly promise to eat the worst-performing student in her class and she then moves a bunch of index cards with the students names around as she sees fit. To which Paul notices Molly is one or two away from the very bottom.
During lunch, both girls tell Paul that he can get ahead by working on extra credit projects and doing well in the Talent Show. In the dining hall, considering there is no room by his friends, Paul sits across the table from a lonely chubby child. They talk with each other and the boy's name is revealed to be Marv. He also learns that all of the other teachers are normal while his own is not. And so, Paul begins to explain every horrible little thing about the teacher to Marv. Only to stop, when both Molly and Celeste drag him away to inform her that Marv is Mrs. Maaargh's son...
Paul then hurriedly decides that he will have to confront Mrs. Maaargh first before Marv can, in hopes of damage control and finds her during her lunch of crackers and mice. Molly and Celeste brainstorm ideas with Paul on what his talent can be. While Paul knows, the girls warn him that Mrs. Maaargh has never laughed at anything before, so if he really wants to do stand-up comedy then he better do something spectacular to dazzle her. Spectacular like doing balloon animals while performing stand-up Paul decides. It is then Marv shows up in Paul and Brad's room and offers them some dessert, but Paul rudely rejects the treat as he suspects the boy is only trying to fatten him up for his mother.
Several days later at the talent show audition, Paul's roommate Brad gets sabotaged when someone pours "pure skunk scent" from the science lab into his violin case, causing a noxious odor to fill the rehearsal hall when he tries to play his instrument. Mrs. Maaargh heads over to the science lab and retrieves a bottle of the skunk scent and decides to drink it. Since Molly and Brad were both competing to play violin in the talent show, Mrs. Maaargh disqualifies Brad and allows Molly to stay in the show. Paul has the misfortune of trying to make people laugh after all the commotion, and he is shocked to discover someone has poked holes in all the balloons, ruining his act. Paul immediately suspects one of his friends. Only to then suspect Marv when he finds a block of the fudge Marv had with him earlier next to a bunch of pricked balloons and Brad's ruined violin case!
After school, Celeste and Molly are working on some sort of model using Nerf balls and sticks. When pressed, they admit they are working on a model of the galaxy. Then they suggest that Paul get in good with Mrs. Maaargh by doing a molecular model of the most complex molecule in existence. Paul decides that extra credit could only help, given that he accidentally stepped on Mrs. Maaargh's foot and severed one of her clawed toes, which she then ate...
When Paul goes on to present Mrs. Maaargh with the model he spent several nights constructing, he discovers that someone has sabotaged him! It now has formed the words 'YOU IS UGLY.' Paul tries to insist someone is out to sabotage him, considering the numerous previous incidents but Mrs. Maaargh only chastises him about his improper grammar, then moves his card out of the chart and on the floor. Over time Paul begins to realize that the telephones do not work in this school and that none of the outgoing mail ever delivers or is even sent. Leading Paul to decide he will escape. Molly tries to tell him it is impossible, and goes on to explain that she tried after a few days of being there when she found out her teacher is a monster. She tried to escape but was caught. Which is why her name is so low on the list. Paul tries to run away, anyway. But is stopped when he sees his parents there!
Mrs. Maaargh has invited Paul's parents to feed them a story about how their son tried to run away, revealing that the forest surrounding the academy as so dense that were he to run away "again," he would be lost forever. Paul realizes she is just covering for his disappearance once she eats him. So he tries to beg and plead with his parents to take him with them, but they refuse...
Finally the day of the big talent show arrived! During lunch, Paul is handed a note from the office and told he is to report to the auditorium immediately. While he waits in the spotlight to go on in the eerily empty concert hall, Molly shows up and informs him that the talent show was canceled, meaning Paul is still on the bottom and was only called to the auditorium to be Mrs. Maaargh's lunch. Paul is lowered down under the stage using the trapdoor as Mrs. Maaargh prepares to eat him. Molly then arrives trying to cause a distraction to save Paul. She then reveals she was the one sabotaging him previously, as she wanted to get moved off the bottom of the chart. But she feels very bad about it and is trying to make up for what she did. She attempts to hoist Paul up on the elevator to the top. Unfortunately, Mrs. Maaargh pulls him back down and only Molly escapes. Paul wriggles free and runs for help, only to bump into Marv. Who tells Paul that he thinks of him as a friend, since Paul was the only person to ever talk to him. He then gives advice to Paul in hopes of helping him. If Paul can make his teacher laugh, she will fall into a coma and hibernate for six months. Paul realizes his jokes will not do the trick, so he resorts to one final tactic! Tickling his teachers wet, clawed toes until she then falls into a deep sleep!
Paul has defeated his monster teacher and is rejoined by Marv... who then tells him he is hungry.