Two murders occur at the event hall where Kogoro is scheduled to attend a speaking event. With the help of event staff Tsukuba Mei, the trick behind the locked room and time of the murder are exposed, and even evidence is found identifying security company president Tsukinogi as actor Inokoshi's killer. She is asked to appear on the panel as the new generation's detective, where she asks the great detective Mori Kogoro about a murder that happened at a certain college one year ago.