Painter Kitasono is murdered. Two of his apprentices visited him on that day, and his apprentice Higashio was the first to discover his body. His other apprentice Nishiyama was painting at Lake Okuho and was late. Nishiyama was working on a painting of Conan, Genta, Mitsuhiko, and Ayumi in front of Lake Okuho. The police look into the alibis of Higashio, Nishiyama, Kitasono's wife Kinuko, and housekeeper Shizu. Conan and friends return to Lake Okuho with Detective Takagi, and...