Conan went to Professor Agasa and obtained a very useful gadget. Conan then arrived at Kogorō's detective agency and keeps thinking what Agasa told him about Kogorō thinking that it is impossible. Suddenly a mysterious woman came to Kogorō's office, which Kogorō later knows that it is the famous Pop Idol Yoko Okino. Yoko explains her situation to Kogorō and decided to go to her apartment alongside with Ran and Conan. When they arrived there, they see a dead man with a knife on his back in the living room of Yoko's apartment, which shocks everyone.