Aviator Dick Moreland uses his winnings from a recent flight to fund an expedition to recover treasure buried by his pirate ancestor. However, Stanley Brasset, another member of Moreland's club, steals his map and sets out to find the treasure for himself. Dorothy Craig becomes involved when Dick needs her car to chase Brasset's henchmen and recover the map, which results in Dorothy being kidnapped and requiring rescue by Dick. When told of the treasure, Dorothy offers her father's yacht to take them to the island. Unable to retain the map, Brasset joins the expedition (his identity as the villain unknown to the protagonists) with henchmen hidden aboard. The henchmen are discovered and attempt to take over the ship en route to the Caribbean but this fails. Brasset releases them again after arrival to stop Dick from recovering the treasure. The treasure chest itself is empty and the search by the two parties continues on the island. Island natives eventually capture Brasset and his henchmen and plan to sacrifice them. Dick intervenes and they are brought back to America as prisoners.