This series is SO good! It's what I like in a Kdrama. Mystery/thriller, light on romance but still heart throbbing and has an AMAZING storyline! The cast and acting are fantastic, not giving too much or too little. It's just right to make it more captivating to watch. I don't pay much attention to the OSTs as I constantly keep my eyes on the screen, but I know it always sets the mood for the variety of scenes that an OST would be playing. All in all, it's still a great series with excellent cinematography that captures action-filled scenes accurately and gets your adrenaline flowing.

Most unliked Parts :
1) why Gye young was killed . if he was a serial killer then why he stoped killing afterwards. and only killed those related to the girl.
2) Gye youung was killed before her father was killed by him so why he put his father on the same place where he killed her.
3) No information on whether he was a psychopath, a rapist or a human trafficker. Nothing, nada. All is left at the imagination of the viewers.