The story begins with a distressed woman hiding an unusually large newborn named Cootie. As he grows at an extraordinary rate, becoming a 13-foot-tall giant by the age of 19, his aunt and uncle, who care for him, keep him confined indoors, fearing the dangers of the outside world. Cootie, curious about the world beyond, is restricted to his new, larger home and spends his time reading, working out, and watching TV.

One night, Cootie sneaks out disguised as a bush and encounters a group of local kids. Felix, one of the kids, discovers Cootie's presence, and the news spreads quickly. The kids nickname him "Twamp Monster" and create t-shirts in his honor. Felix and his friends, Jones and Scat, continue to spot Cootie from outside, setting the stage for further interactions.