Johnny Kapahala returns to Hawaii to attend the wedding of his grandfather, the legendary Johnny Tsunami. But instead of catching a few waves while he's in town, Johnny's got his hands full keeping an eye on "Uncle Chris," the 12-year-old son of his grandfather's fiancée. Through Chris, Johnny is introduced to the "Dirt Devils" - the local dirtboarding team. When the Dirt Devils wind up in direct competition with Grandpa's surf shop, it's up to Johnny and Chris to join forces and save the day.