Together, Marina, Aqua and Oceana are the Petticoat Pirates! Living aboard their ship in the Periwinkle Lagoon, they are surrounded by the magical high seas which hold all sorts of adventure. One day, three beautiful mermaids come to the lagoon to ask for help. A creature of the deep has come and set loose all the sea snails on their mer-farm, leaving behind nothing but a shiny scale. Can the Petticoat Pirates discover what happened and bring the sea snails back safely? One thing's for sure, they'll need all their pirate skills to solve this mystery!