Miike Naeko of the MPD Transportation Department goes to karaoke with her colleagues Yagi Shiori and Momosaki Toko. On the way home, Momosaki is attacked once she's alone, and her body is discovered the next day. One week earlier, Momosaki and Yagi arrested Aono Kengo, Akamine Manji, and Shiroyama Yuzo for traffic violations and got into a fierce argument, and the police believe it may be related to this case. Meanwhile Yagi goes to visit a certain individual.

With the help of Conan`s detective skills, the identity of the culprit who murdered MPD Transportation Department officers Momosaki Toko and Yagi Shiori is determined. Additionally, the police learn that one week earlier, the culprit heard the name "Yumi" while he was being disciplined for a traffic violation. Though the name referred to someone else, based on the victims` mutual acquaintances, it`s possible that Transporation Department officer Miyamoto Yumi may be his next target, and the search for the culprit begins. However, no one can get in touch with Yumi.