Ran, Sonoko, and Sera head to a practice studio with Conan and Amuro so they can form a high school girl band. There they spot guitarist Someka, bassist and vocalist Tadako, keyboardist Rumi, and drummer Hagie. Later, Hagie is found strangled in the studio where she had been napping. The three band members who went to wake her one by one are suspected of killing her, but when the police can't find the string used to kill her, the investigation encounters some trouble...