Ryan Jeffers is a middle school student whose leg disability keeps him from trying out for sports and makes fitting in a constant battle. He serves as the waterboy for his school's football team and harbors a quiet crush on the quarterback Brad's girlfriend. To cope, he escapes into comics and daydreams about daring adventures, masking the real sadness his condition brings from his mother.
One night, Ming gives him a manuscript of Tao that symbolizes the five elements—Earth, Fire, Water, Wood, and Metal—and urges him to live fully despite his limits. That same evening, Chucky pushes him toward an initiation with Brad and his friends, guiding them to a water plant where Ryan must cross a narrow pipe to sign his name on a wall of graffiti. Ignoring Chucky’s protests, Ryan steps onto the pipe, a hidden mechanism opens, and he is dumped into the water.
He awakens in a puzzling forest, is briefly attacked by assailants drawn to a lake-born creature, and discovers that his leg now works. He meets Mudlap, a dwarf-like man, before a beautiful girl named Elysia drives him away. She explains that he is in Tao, and he recounts the manuscript he lost in his backpack. Believing it to be the Manuscript of Legend, Elysia takes him to Master Chung, where they meet four of the five elemental warriors—Lai, Chi, Tsun, and Yee. They learn that Yun, the Warrior of Water, left them after an old conflict, and that Komodo, a warlord who betrayed the Warriors, is chasing the Lifesprings of Tao to stay young forever.
Ryan is captured by Komodo’s henchmen—Mantose, Barbarotious, and Dullard—but is rescued by Yun. He convinces Yun to return to the Lifespring. Yet Mudlap betrays him and leads him into General Grillo’s grasp, while Chung rescues him again. Yun, Yee, and Chi pursue the manuscript but fall into a trap after Elysia betrays them and joins Komodo in a vengeance-seeking plot for killing her brother by accident. They barely escape and return to the Lifespring to thwart Komodo’s ambush.
Komodo battles Chung and kills him, then escapes with Ryan. Waking in Komodo’s palace, Elysia pleads with Ryan to read aloud from the manuscript so Komodo can breach his world for more Lifesprings. Ryan realizes he cannot read the book, which enrages Komodo, who strikes at him. Elysia intervenes and is slain by [Barbarotious], while Komodo kills Barbarotious in a rage and sails back to the Lifespring to challenge the Warriors in a one-on-one showdown, splitting into five versions of himself.
Ryan, after receiving an apology from Mudlap for his earlier betrayal, discovers a hidden inscription in the manuscript. He tricks Komodo into overusing his power, weakening him enough for the warriors to cleanse his spirit and reform him into a kinder man, purifying his army in the process. Mortally wounded, Ryan is surrounded by his friends, and Yee astonishes everyone by thanking him, speaking for the first time in years.
In a sudden twist of fate, Ryan finds himself back at the water plant and, when faced with a chance to prove he can fit in, chooses not to cross the pipe. The trap seals Brad on the far side, and the disappointed boy is left to face the police. That night, Ryan apologizes to his mother for an earlier argument and, as he drifts to sleep, tells his dog about Tao.
