Planning on sailing his schooner, the Laughing Lass, to his ancestors' treasure island in the South Seas, veteran seaman Obadiah Wolf makes his last payment on the vessel to Ellory Glendenning, a crook who hopes to cheat the old man out of the boat and then sell it to the government at an outrageous price. Learning that Obadiah has a treasure map tattooed on his chest, a pirate called "Bad-Eye" forces the old buccaneer to accompany him to the island. Meanwhile, Ellory and his son Harold seize the Laughing Lass, ordering Rory O'Malley, who is loved by Obadiah's granddaughter Patricia, to sail it to the South Seas so that Harold may evade the draft. During a storm, Rory and Patricia take control of the schooner, and soon they too land on the island. Rory and Patricia unearth the treasure and then rescue Obadiah from "Bad-Eye," whom they leave on the island. Upon the party's return home, Ellory is obliged to give the ship back to Obadiah and his son to the U.S. army.