With them being secure from the police, the culprits decide to find the remaining children and silence them once and for all to ensure the smoothness of their plan: to have the daughter of their original victim bring the ransom, lock her into the building, and eliminating all witnesses by setting it on fire. While one scours the empty building, the other remains behind in one of the rooms on the fourth floor, with Conan and Ai kept tied up and gagged in the open and their other victim sealed away in a locker. But what the two don't know is that Ayumi, Mitsuhiko and Genta have actually managed to slip into the very same room and hidden themselves in one of the lockers, now able to overhear the two culprits safely but unable to reveal themselves in order to rescue their friends! However, Conan has managed to grab hold of his Detective Boys Badge and, taking a leaf from the kidnap victim, he begins to tap messages based on the Tokyo Fire Department emergency codes to his hidden friends. Deciphering the messages with the help of Mitsuhiko's note book, they gradually begin to understand that Conan wants them to call their individual cell phones, which have ended up scattered all around the building, matching the codes he transmits with the cell phone wallpapers in order to play through a chaotic sequence and thereby to draw the kidnappers out of the room. The plan eventually works: Frazzled with their continuous lack of success in apprehending the kids and contacing their kidnapee's daughter, the second culprit temporarily leaves the room in order to help in the search. The culprits eventually come behind the ruse, but by the time they react, it is already too late: Conan knocks their guard out with his tranquilizer watch and prepares to ambush his accomplice, unaware that the latter has in the meantime encountered someone on the stairs. And now ominous footsteps are approaching... (thetvdb.com)