Looking for his brother who disappeared searching the South Pacific for the lost city of Tobanya, archaeologist Dr. Irwin Hayden, his daughter, Leslie and his assistant, Link Simmons, seek a treasure chest on board a sunken ship in a remote archipelago which they hope will provide clues to the missing man's whereabouts where they are joined on their quest by Morgan, a shipwrecked merchant mariner, and his sidekick Chongo. They are pursued by a gang of heavily armed modern pirates and tribes of cannibals.