Marilla and Jerry are two merfolk who live in the waters of Port Stephens, where they have many friends in the sea and on the shores. Years ago, when she was very small, Marilla's parents disappeared. Now she only has her grandmother to care for her. On a trip with her dolphin friends up the east coast of Australia, Marilla learns of the mystery of Esmeralda Cove. Convinced it involves the fate of her lost family, she is determined to solve it. Marilla and Jerry embark on a dangerous adventure.
