Conan, Ran, and Kogoro are on their way to a Y?ko concert when Kogoro discovers he lost his ticket. He overhears a woman named Masayo on the payphone and her situation about a friend who is unable to go to the concert because of a cold. Kogoro asks her for the spare ticket and she accepts as long as Kogoro drives her to her house to pick up her sister. Masayo finds the bathroom sealed with tape and when they break through, they find Masayo's sister dead. Everyone believes the death was a suicide, but Conan knows its murder.