The annual Qixi Festival is approaching, but six serial murders have occurred in Tokyo, Kanagawa, Shizuoka, Nagano, etc. The victims left seven cylinders and strange hints in mahjong tiles. Due to the large scope of the crime, detectives from various police stations have gathered in the Tokyo Police Department's task force to study the case. Maori Kogoro was also invited to participate, and Conan secretly listened to the contents of the meeting. After the meeting, Conan accidentally heard the nursery rhymes sung by Gunma County Police Department Yamamura So, and then discovered that members of the Black Organization had mixed into the police. During a round-up operation, Conan met Vermouth, who was posing as a hostage, and learned that the recent series of murders were related to memory cards containing information on personnel inside the organization. At the same time, the spy who infiltrated the police secretly stole the fingerprints of Kudo Shinichi and Conan. The identity of Shinichi was exposed, and a huge danger was rapidly approaching him and the people around him...