Masquerade Night

An anonymous letter is delivered to the police - a warning that the killer involved in a mysterious homicide that occurred a few days ago in a condominium in Tokyo will strike again at "Masquerade Night", the New Year's Eve countdown party held at Hotel Cortesia, Tokyo. All 500 invitees will be in costume. Everyone is a suspect. As the masked guests begin to arrive, they struggle to find a clue which will lead them to the murderer.

Midnight draws near as the number of suspects increases. What is the killer's intention? Who is the informant? Will Nitta and Yamagishi be able to unveil the truth hidden behind the murderer's mask before the time limit?