The novel follows the adventures of Sam Steele and his friends, Archie Ackley and Joe Herring, who are known as the "Boy Fortune Hunters." The story picks up after their previous adventures, with the boys now setting their sights on the South Seas, lured by the promise of treasure and adventure.The trio embarks on a thrilling journey across the Pacific Ocean, navigating through dangerous waters and encountering various challenges along the way. Their goal is to find a hidden treasure that is rumored to be buried on a remote island in the South Seas. The treasure, said to be left by pirates or ancient civilizations, is the key to the boys' fortunes.