Max is a lonely 10-year-old boy with a vivid imagination. His life at school is difficult, with bullies taunting him and teachers misunderstanding his creative nature. To cope, Max creates a dream world called Planet Drool, filled with imaginative characters like Sharkboy, a boy raised by sharks, and Lavagirl, who can produce fire and lava. One stormy day, these fantastical characters come to life and urgently seek Max's help. They explain that Planet Drool is in peril, corrupted by an evil mastermind known as Mr. Electric. Max is amazed but uncertain about his place in this adventure.

Despite his doubts, Max joins Sharkboy and Lavagirl on their mission to save their world. The trio embarks on a perilous journey, navigating through various dream-like landscapes that represent Max's imagination. Throughout their quest, they aim to defeat Mr. Electric and restore balance to Planet Drool. Along the way, Max learns valuable lessons about friendship, courage, and the power of dreams. As their adventure unfolds, Max's perception of reality and imagination begins to blur, and he discovers the true significance of his role in the fate of Planet Drool.