Sakaki Mariko attends an annual concert held by the Kyoto Prefecture Police Music Band. At that time, Mariko hears from Domon Kaoru that a woman's dead body is found under a cliff. The victim is Konno Megumi, and she was murdered. The fingerprint of Katsumata Toru is found on the guitar which belonged to the victim. Toru is a guitarist in the police music band. As a result of the examination of musical instruments belonging to the police music band, Mariko and Kaoru discover a hidden truth behind Megumi's murder.