A person who murders people with a hammer dubbed "Hammer Man" has be spotted after a murder heading to an apartment. Sato and Takagi stalk out the apartment. After realizing there was no activity in the apartment, they enter the suite and find a man who's hanged himself. They then realize that the man who hanged himself is not the hammer man and that the culprit has impersonated a delivery worker and escaped.

A blind rich woman named Shoudo Kuromi asks Mouri to help her find a boy who saved her life in the past;the only clue is that the boy should have a large scar across his torso. She has been able to narrow it down to two people and they are both staying at her house. Conan meanwhile notices the police are stalking the woman's house. Kiyonaga Matsumoto tells Conan that a serial killer from a past case may be there as the killer also has a scar across his chest. During a bath, Mouri notices that the butler also happens to have a scar across his torso.