After a Texas cowboy jumps ship off the coast of Kauai, a 12-year-old-boy rescues him from drowning. While Costain waits to return home, he decides to help the boy's mother's failing potato plantation by turning it into a cattle ranch. But first, he must outwit an unscrupulous businessman, an evil witch doctor and turn the easy-going islanders into ridin' and ropin' cowpokes.