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. I would recommend this for thriller lovers or those who are light on romance but love the action with an interesting storyline <3