Heiji and Kazuha arrive at the Mori Detective agency revealing he was hired by a man named Shinichi Inubushi, one of the eight illegitimate children of the rich Tsunechika Inubushi. After Tsunechika's death, the health of his wife, Satomi, begins to fail and subsequently two of the illegitimate children are murdered. Believing the murderer is after the inheritance, Shinichi surrenders his share and takes up his mother's surname, Kudo, and has Heiji investigate the murders. Heiji and Conan drop by Kudo's home only to find out from his personal care assistant, Funae Abukawa, that he is asleep. After half an hour, they discover Kudo dead from Carbon monoxide poisoning caused by a single charcoal burner. Their investigation reveals Abukawa is the murderer, as Kudo's body revealed he died much earlier and a single charcoal burner would take too long to fill the entire room.