Kogoro is invited to a mountain house by a previous client named Hiromi Yamazaki who wishes Kogoro to help with the announcement of a spa resort. While Kogoro is looking out the window, Hiromi falls from the second floor and is announced dead. Evidence show Hiromi was attacked by bees and accidentally ran off the balcony, but Conan believes there's more to the story and does an investigation of his own. Using a knocked out Kogoro, Conan declares the housekeeper, Shingo Aihara, as the killer who used Hiromi's apiphobia to his advantage and other tricks to ensure Hiromi fell to her doom.