Leialoha and Keilani, best friends and cousins, are the princesses of Okalani. While their titles indicate they might sit around in pretty dresses all day and attend tea parties, that's not the case for these two. They live in a beautiful palace on a tropical island, but like all girls around the world, they manage to get into plenty of mischief. Their goal is to stay in the good graces of the stern Queen Makaha. Leialoha and Keliani plan to spend the last week before school starts having fun, including celebrating Leialoha's twelfth birthday. They intend to explore the island and swim with Nani, a bottle-nosed dolphin. But on one of their expeditions, they discover a group of dangerous men on the island who have a mysterious purpose. From humorous mishaps with the queen, to spying on the strangers and putting the clues together, the girls embark on a quest to save their beloved dolphins.