Saki, who may have incurred the enmity of Tatsuko, Tachibana, and Michiyo, dies after falling from her apartment. Conan determines her death was not a suicide but a murder. He deduces that Saki was blackmailing one of the three using something she witnessed, and they killed her in order to keep her quiet. Conan and his friends tell Detective Takagi about the three suspects, and since Tatsuko has an alibi, he goes to question the other two. The police believe Michiyo murdered Saki after her secret was discovered, but something doesn't seem right to Conan...

Kogoro arrives in Okura, Fukuoka with Conan and Ran. Kogoro's senior and company president Fukamachi accidentally fell and is unconscious in the hospital. Managing director Kiriyama hires Kogoro to catch the culprit who graffitied the office. Meanwhile, Ran meets suspected vandal and Fukamachi's son Torahiko. Torahiko insists he didn't do it and is conducting his own investigation into who pushed Fukamachi. Eager to solve the case, Kogoro gathers everyone involved including Torahiko at the office and begins explaining his reasoning, but...