In the Cartoon Dimension, Matt Falletta as Doctor Carnage conducts a brutal experiment on a man, disemboweling him and ripping his skull out through the stomach. Across dimensions, on Earth, sisters Beverly Lynne as Cindy and Lizzy Borden as Candy are left alone with Cindy's friend Kaycee as Amy. When Cindy and Amy call over Brandon Ellison as Rick and Fernando Padilla as Eddie, the tension starts to rise. Candy, meanwhile, has just received a surprisingly sinister Terror Toons DVD from Satan, a video that follows the antics of Doctor Carnage and his accomplice Scott Barrows as Max Assassin, a stolen lab monkey mutated into a monstrous gorilla by Carnage.
The night grows darker as Candy slips the DVD into a player and the movie bleeds into their reality. During a game of Strip Ouija, Candy nods off, and Carnage and Scott Barrows as Max Assassin materialize in her room. The two replay their brutal show: they rip Candy's spine out, behead her friend Tommy—Fernando Gasca as Tommy—when he drops by, and dismember a pizza delivery man with a gigantic pizza cutter. Their eerie, hypnotic disco dance sends shivers through the house, causing Eddie to vomit up his own innards. When Cindy, Amy, and Rick try to escape, every door in their world twists into vertigo-inducing spirals, trapping them in a maze of looping stairs and crooked halls. Rick is taken, his brain subjected to Carnage’s macabre experiments, and a released-from-Terror-Toons police officer is blown up by a hidden dynamite stick tucked inside a box of donuts, severing the group’s chance to stay together.
Cindy is eventually captured by Carnage, and along with the lobotomized Rick, she is forced to watch as Carnage and Max Assassin saw Amy in half as part of a cruel magic act. The duo then transport Cindy to a cartoon version of Hell and present her to the Devil, who explains his plan to unleash Terror Toons to ravage the Earth and corrupt children. Realizing that anything truly can happen in cartoons, Cindy undergoes a wild transformation into a superheroine and challenges the Devil, who hurls her back to her own house. There, Cindy discovers a machine producing Terror Toons DVDs and is attacked again by Max Assassin. With her new powers, she snaps his neck and stomps his brain out, then turns on Carnage when he charges with a giant axe, slicing his head in half. Tiny monsters spill from the fissure in Carnage’s skull, and Cindy wrecks the Terror Toons DVD press with a crowbar, ending the immediate threat and severing the supply of monsters.
When Cindy and Candy’s parents return home from a wedding, they find Rick banging his head against a wall while Cindy laughs hysterically, surrounded by the wreckage of her friends and sister. Next door, a boy discovers another Terror Toons copy in his mailbox and rushes inside with it; the front door slams shut, and Carnage’s giggle echoing from the unused DVD lingers in the air.
