In Miami Gardens, Florida, a 12-year-old boy scientist Cody testing the Scum Serum on some plants for a science fair project. In school, there are three students, a 10 1/2 year old brown-haired boy named George, an 11 year old redhead girl named Lizzie, and an 11 1/2 year old black-haired boy named Ralph. During his school's science fair, there are four vials, one with a picture of a gorilla on it, one with a picture of the iguana on it, one with a picture of a wolf on it, and one with a warning label on it. Tommy tries to test the serum, but when the experiment gone wrong, he accidentally exposes his classmates, the gorilla DNA into George, the iguana DNA into Lizzie, and the wolf DNA into Ralph, and the chemical mixture into all three siblings, then something happens. They begin growing, their muscles become bigger, George starts growing hair on his body, Lizzie develops scales, spikes and sharp teeth, and Ralph grows hair and a dog-like snout. Before anybody can say anything, the three students are now 30-foot tall monsters. George is a giant gorilla, Lizzie is a giant dinosaur-like creature, and Ralph is a giant bipedal wolf.
- George - A 10 1/2 year old brown-haired boy who has mutated into a giant 30-foot-tall gorilla-like monster similar to King Kong.
- Lizzie - An 11 year old redhead girl who has mutated into a giant 30-foot-tall dinosaur-like monster similar to Godzilla.
- Ralph - An 11 1/2 year old black-haired boy who has mutated into a giant 30-foot-tall werewolf-like monster.