Heiji, Kazuha and a man named Kasukawa are held hostage in an attic of someone's home. Meanwhile, Conan, Ran, and Kogoro are tired of waiting for the two and begin searching for them based on clues from the last phone call. They investigate Detective Kasukawa's home and discover evidence that Heiji had been there. Conan finds a memo which discloses Kenbashi City, Ito Residence. They investigate those with the surname Ito but are unable to find information about Heiji. Meanwhile, it is revealed Heiji is held hostage by Misari Ito, an attorney who is the head of a tax evasion group. Ito demands Heiji to solve a code made by Kasukawa which contains a seven-digit-code to a safe box containing evidence of her scandal.