Kogoro receives a request from a client named Ryouzou Gamou to find a witness to confirm his alibi. On the sixth day Gamou calls Kogoro and tells him he has lost hope in him. The next day, Gamou is found hanged in a forest an hour in distance away. The police suspect it to be suicide but Mori reveals it is a murder, as Gamou could have killed himself at home if he wanted to. After interrogating Gamou's nephew, Kyousuke Arai, Kogoro returns home to find news reporters who question Kogoro about the suicide revealed to be murder. The next day, Kogoro heads to the horse track and meets up with detective Isao Takeoka, the detective who falsely accused Gamou five years ago. They work together and investigate Ryouzou's ties and end up at his nephew's house. They interrogate Arai and reveal his motive for the murder would be the inheritance. The next day, Arai is found in his house hanged and Kogoro decides to close his detective agency by removing its sign.