Yukiko brings Conan, Ai and the detective boys to watch a Kamen Yaiba movie preview. Once there, they find out the movie has been delayed to later that night. Yukiko having to leave to catch her flight to America, leaves the kids in the care of Akira Hojima, one of the four employees of the Kamen Yaiba film. Before leaving, Yukiko tells Conan to be careful of the black car that has been following them. Akira takes the kids to his apartments near the studio and invites his fellow employees to a game of Mahjong. While everyone is asleep, they are awakened by a scream and find the salesman Furumura Norihiro murdered with a knife. Conan wonders how the murder was done in an impossible to see darkness without making a sound in a messy room.