The movie is a cross between "American Psycho" and "Infernal Affairs". It just doesn't do it in terms of quality of the scenario, or probably the way some actors play. Only the psycho was halfway decent. It could have been better if some of the actors just avoided to show they were acting by overdoing it, like the comical moments or some dramatic ones. The story would be good, but there were little things that prevented me to appreciate it. The ending should have stopped when the villain is done and dealt with, but there was an addition, which annoyed me. I saw similarities with the other Korean movie ("The Host"), in that I can't decide whether I should be happy or sad about the character, if not the movie.