Johnny Kapahala, a teen snowboarding champion from Vermont, returns to Oahu, Hawaii for the wedding of his hero--his grandfather, local surf legend Johnny Tsunami--and to catch a few famous Kauai waves. When Johnny arrives, he meets his new family including "Uncle Chris", his new stepgrandmother's 12-year-old son, who resents the upcoming marriage and whose only interest is to join a mountain-boarding crew led by a teenage bully. When Johnny's grandfather and his new wife open a surf shop that also caters to mountain boarders, they are soon embroiled in a turf war with a rival shop-owner who wants to shut down their business. Chris' antics cause complications for the store-opening and the wedding, but eventually he reaches out to Johnny, who helps him find his place within the new family and settle the dueling sports-shops' turf war.