I've always enjoyed watching this kind of series and this one is no exception. However, how much the beginning was good and promising that much towards the ending plot became ridiculous and without a sense. No, I'm not trying to tell you not to watch it, it's even opposite, watch it and you'll see and meet one the best villian and psychopath EVER. Lee Joon potrayed a great, mad, twisted, crazy, unstable and psycho man that every time I saw him I got chills all over my body. His acting was so believable and real that I sometimes wondered if he's like that in real life and I would give a 10 for that. Yes, there are many flaws in this drama, besides that they made cops look totally ridiculous and clueless, I didn't like any of the female characters in this drama. Maria was the hell annoying and ridiculous trying to be something that she is NOT. Honestly, if I have to choose between her and Ji Wool it would rather be Ji Wool, 'cause at least she tried to help and understand Ryu Tae Oh, even if it's putting his life on line. Yoon Sang Hoon did a best job in a character of a detective. For me, he tried his best and totally succeeded in it. Ah, Sung Dong Il ahjussi... it's always a pleasure to watch him with a no exception this time too! Overall I enjoyed this drama, but I think if they packed it all in 16 episodes this drama would have a higher rating and it would be a better watch. l've liked Lee Joon's character, even though he was bad, but there was something great about him and his mind. His craziness was driving me crazy too! OSTs were really good, especially main song and all those kinds of instrumental played in this drama giving you a thrilling and exciting feeling. For those who love thriller and suspense genre with a many twisted characters that at some point you want to go into their heads and understand what they're thinking, is totally not to miss!