One thing about this drama: You can't really hate anyone, even the evilest monsters here you can't really hate them. Because they are so good at being evil and their personalities and thoughts are so deep that one can only slow clap and admire such cleverness. The writer tries to make us -in some way- understand them and understand the reasons of their actions. The drama sets the premise that there's no evil or good action that isn't justified, whether it's right or wrong doing that, there's still a "valid" reason to do that in someone's point of view. We literally get into the mind of a psychopath. The interactions between every character (mainly the main lead and his enemy) are pure gold. Each one of their scenes is so cleverly done that you just want more and more scenes of them talking or interacting in some way. The characters, my god! Every character is important, every character is multidimensional and necessary for the plot development. It feels that they are not just simply fictional characters but real human beings living their lives, struggling and bonding. The acting is superb! I have 0 complaints about the actors job. It was PERFECT. Spoilery part, BE CAREFUL!! The only reason I didn't give this drama a perfect 10 is that I wasn't surprised at all about the main mistery. The drama sets some "misteries" about who is the lost brother or the evil serial killer but I already knew who was who since episode 4, so I felt kinda disappointed because I wanted to be surprised, is probably not the drama's fault, maybe is my fault haha but I wanted to be surprised by this and I just wasn't. But the rest of the drama was perfect.