A man running away from a police officer stumbles into the Detective Boys, grabs Ayumi as a hostage but collapses. They see a big wound on the back of his head and move him to Beika Hospital. He has no identifying papers on him, only a torn piece of magazine paper, seeing which, the police decide that he was attacked and decide to protect him. The doctor who comes out of the surgery starts acting suspicious when he hears Mauri's name. Conan and the Detective Boys track back the places the man has been to - realizing he had the wound for quite a while - and finally find themselves at the backside of Beika Hospital.