Drag of a show. the police is shown as incompetent. After all the evidence pointing towards the residence, no police or detective investigates the residence even after A DETECTIVE goes missing.
IMO the story could have been much better but some senseless scenes like the dentist reaching the reporter out of nowhere and killing him in broad daylight as if he has eyes everywhere and can teleport anywhere. The directors have been stubborn in forcing their story rather than trying to make sense out of it. the start was amazing but the wheels came off IMO after a few episodes.
Character development has been poor as no background story on the killers(twins, pervert & dentist).
The role of Jung-on's mother and office collleagues is insignificant only to drag the series.
Overall, a 2/10 performance considering the standards of Korean shows. Not so easy in real life for a killer to kill everyone so easily and get away with it while living in populated urban society.