Snowboarding hampion Johnny Kapahala travels to Hawaii to for the wedding of his grandfather - the legendary Johnny Tsunami. He's much looking forward to conquerring some wild waves there besides family time. But the fact is he has no time for this and must keep an eye on "Uncle Chris," the 12-year-old son of his grandfather's new wife who is not happy with the wedding instead. Through Chris, Johnny is introduced to the "Dirt Devils" - the local dirtboarding team led by a bullying boy. When the Dirt Devils plots to bring Grandpa's new surf shop down, it's up to Johnny and Chris to join forces and save their family's business.