A detective (Takuya Kimura) sneaks into a hotel disguised as a waiter and investigates a serial murder case with the hotel receptionist (played by Masami Nagasawa). Directed by Masayuki Suzuki. Three murders occurred in Tokyo. The police deduced from the unexplained number series left at all the crime scenes that this was a series of serial murders with foreshadowing information, and launched an investigation. The elite detective Nitta Kosuke (Takuya Kimura) of the Metropolitan Police Department's Investigation Division deciphered that the number indicated the location of the next crime, and he deduced that the Tokyo Cortasia Hotel would be the scene of the fourth murder. However, there was no clue as to who the murderer was. The police therefore decided to sneak into Tokyo Cortasia to investigate, and Nitta had to pretend to be a front desk staff to track down the murderer. The person who was ordered to guide him was Naomi Yamagishi (Masami Nagasawa), an excellent front desk employee of Tokyo Cortasia. Faced with the guests of unknown origin who appeared one after another, Nitta, as a criminal policeman, "puts arresting criminals as the first priority" and tries to peel off the "masks" of the guests, while Shangmei, as a hotel staff, starts from the principle of "ensuring the safety of guests as the first priority" and hopes to protect the "masks" of the guests. The two are like water and fire. Nitta and Shangmei clashed several times because of their different positions. However, as the undercover investigation progressed, they gradually understood each other's values as professionals, and an incredible trust relationship began to sprout between the two. In this process, the case developed rapidly. Both the police and the hotel were forced into a dilemma with no way out.