When Kogoro Mouri goes to his alma mater for a "speech", Ran, Sonoko, and Conan end up going with him. Sonsaku Tsujiei, a 4th year student at Beika University, wants Kogoro to look at the haunted house and evaluate its accuracy. When Kogoro takes too long during his speech, Conan, Ran, and Sonoko decide to check out the haunted house themselves. Sonsaku and Hachiya Kiichi (a colleague) escort them into the haunted house only to later play tricks to scare them. When they are in the "Operating Room", Anna Tadami, the victim, is playing the patient during the operation. When the trick is over, everyone realizes that Anna hadn't finished her part. When they try to get her to wake up, Conan realizes she has been poisoned by cyanide.

Due to a recent fad, Sakamoto Ryoma histories have become popular. Capitalizing on this, Jirokichi Suzuki's museum has set up a Ryoma exhibit. Jirokichi wanted to purchase a prize item of Ryoma's for the exhibit, a gun belt with a large ruby, from the current owners Shishihiko Tarumi and Masanosuke Hanamura. Not wanting to buy it before having it evaluating by his own appraiser, Jirokichi instead arranged a space at the exhibit for the owners to display the gunbelt in the meanwhile. Elsewhere, Sonoko tells Ran that Kaitou Kid has sent an advance notice that he will be at the exhibit to return some items that were stolen 20 years ago from Shishihiko Tarumi's Ryoma exhibit by the thief Phantom Lady: Ryoma's letter to his wife talking about the belt, a pistol Ryoma was carrying, and a sake cup with a bloodstain when Ryoma was assassinated. Inspector Ginzo Nakamori and Superintendent Shintaro Chaki discuss the best strategy to capture Kid: Lure Kid in to allow him to to return what was stolen, but then prevent him from leaving.