13 years ago, Shinichi and Ran met at kindergarten. Shinichi tells Yusaku and Yukiko about the suspicious behavior of Efune, a teacher who favors Ran. The next day, Efune takes the children to the park far away from the kindergarten. Yusaku goes to check on the children while dressed in disguise and witnesses the driver of a parked van taking photos of the children and smiling. Later, Yusaku learns Efune's wife is staying at the hospital next to the park and begins to realize Efune's plot...

Kogoro and Conan search a fourth floor apartment when they're asked for help by the trio standing in front of the room: Saki's friend Maiko, building manager Yoshie, and deliveryman Matsuda. Inside they find the bodies of residents Maehara and his wife Saki. Day trader Maehara had recently made a lot of money, and the valuables are missing from the apartment. Inspector Megure deduces from the apartment's condition and the testimony of the trio that Saki pretended to be a robber and murdered Maehara, but made a mistake while disguising herself as a victim and suffocated herself. However, Conan notices something strange about the crime scene...