The Detective Boys follow Detective Chiba after they see him purchasing a large amount of food at the convenience store. He enters an ordinary apartment building. The kids wonder if he's come to visit a friend, but Conan explains that the building is... (more) new and deduces that Detective Chiba must be conducting a stakeout here. They follow him inside, where they find Detective Takagi as well. The Detective Boys ask to stay until the professor can come pick them up and learn that the police are staking out this building because of the jewelry store robbery that occurred the previous week.