Kogoro is asked to give a lecture to commemorate the renovation of HISHIDA Hall, and Kisaki Eri is scheduled to participate on a panel. The day of the event, panelists security company president Tsukinogi Hideki and actor Inokoshi Kenichiro come to greet Kogoro in his dressing room. Later, former manager Reizei and hotel owner Hishida Junko get into an argument. And 20 minutes before the lecture, Inokoshi is found murdered in his dressing room. Based on the conditions of the crime scene, Conan judges the case a locked room mystery...