Prince Ivandoe and Bert reluctantly agree to bring Princess Syllabob, of the Underwater Kingdom, an all-powerful Trident for her Sweet Sixteenth birthday. However, it is currently in the possession of Ivandoe's great nemesis — Prince Svan — who has found another, less dignified, use for it. Ivandoe and Bert must risk all, entering the Swan Palace and avoiding the appalling Royal Family, in order to fulfill their promise to King Axalotyl, King of the Deep.