Frank and Belinda Winston are secret agents from the country of Maslan who must go to the unfriendly island of Antoria to try to get back the Pearls of Maslan. These pearls have been stolen by Claude Kradic, a jewel thief. On board the ship to Antoria, the Winstons meet Donna Hill, who will take them to Kradic. But Donna seems to know too much about the Winstons ... Can they trust her? Will they get back the pearls?