Koumi Island's allure lies in its lush hills and captivating coral reefs, drawing tourists seeking the legends of Anne Bonnie and Mary Read. The museum displaying the pirate duo's weapons fuels the island's tourism. Accompanied by his daughter Ran, her friend Sonoko, the Detective Boys, and Conan Edogawa, the renowned Kogorou Mouri visits the island. A room mishap at the hotel leads the group to encounter treasure seekers and immerse themselves in the island's treasure hunt frenzy. While the Detective Boys embark on their own quest, Conan stumbles upon a murder in treacherous waters. Soon, the police, prompted by a robbery clue, swarm the island, plunging Koumi into turmoil. As treasure hunters and locals scramble for the legendary loot of Anne and Mary, Conan, Kogorou, and the authorities pursue a different prize: justice amidst the chaos.