A single woman was murdered, and the police received a tip-off letter stating that the murderer would appear at the New Year's Eve party at Tokyo's Cortesia Hotel at 11 p. M. On December 31.
Detective Nitta pretends to be a hotel receptionist and joins forces with hotel staff Shang Mei to find the only murderer before midnight on New Year's Day while protecting the disguises of all other guests.
The structure of the trilogy is quite novel