While at a cake buffet with Genta, Mitsuhiko, Ayumi, Haibara, and Professor Agasa, Conan and company meet Kitami Saya and Shono Kyona, two actresses who hate each other. One threatens to expose the other if they aren't careful. Not long after, Kyona was found in her hotel room dead, but the room was completely locked.

While Takedera Hitoshi was wearing a costume, his coworker saw him and became frightened, which ultimately caused him to slip and fall to his death. While there were no malicious intentions, he still caused an accidental death, and it's unlikely he'll be cleared of charges. Yet, after questioning office workers who witnessed the incident, Conan and the Detective Boys suspect there may be more to the case.