The Big Investigation of the Nine Doors
daisousaku kokonotsu no doa

Conan, Ai, Mitsuhiko, Genta, and Ai are walking down the street when they hear something fall behind them. They turn around to find an S-hook hanger with a ring attached to it. Ai finds another S-hook hanger nearby, and they connect the S-hooks and ring together to form SOS. Someone was calling for their help from the apartment building nearby.

They manage to get inside the security doors and begin their search. The ring has the words "M to A" etched on it. The size of the ring is pretty small. The woman's name starts with the A. They begin to each the mail boxes and apartment doors for a couple, the man's name starting with M, and the woman's name starting with A. When they find one, they start asking around about them. One woman they come across is very annoyed and snaps at them before she closes the door. Two people come out, dressed in black, like punk rocksters. The woman tells the man that he was too rash when he killed. The Detective Boys run out in a hurry and come across two police officers on bikes. They get them to confront the couple, but it turns out that they didn't kill anyone, but a bug. They are the couple that lives there. The police get pissed off and leave. The detectives know that there's definitely right, that there's someone who needs their help.

Conan realizes something about someone's shoes and goes back inside leaving everyone else stuck outside. Conan goes to the apartment with the angry woman they came across earlier. He confronts the woman and tricks her into saying she's the guy. He stuns her and releases the woman who the ring belongs to. The police are called and Mitsuhiko, Genta, and Ayumi are annoyed that he took all the credit again. They pile their bags onto him and walk away, Ai does the same.