After rescuing a treasure chest from a sunken ship, the crew is shocked to find an elderly woman stowed away inside. To secure passage with the Straw Hat Pirates, she entices them with the allure of a fabled golden crown located on her home turf, Mecha Island. As they reach the island, the crew faces an initial assault from the island's ruler. However, a twist occurs as the lord enlists the pirates' aid in unraveling the enigma surrounding the coveted Golden Crown.