Wow. I don't know what to say about this drama, especially as someone new to watching K-Drama. It was just excellent in every way imaginable. Heavy spoilers ahead, do NOT read this AT ALL if you haven't watched this hidden gem.

It was pure thriller. Something which another thriller drama (*koff* The Game: Towards Zero *koff*) lacked. It doesn't waste your time stringing you into character romance, but rather strings you with layers of character backstory, even for characters you can consider minor.

The characters are amazing themselves, on some episodes, I could even feel the synergy between Hyun Jae, Sooyoung, and Ha Young. But let's not forget to credit the actors who did well with their role, even the child actors! I was really disturbed by the main villain's backstory due to the young actor portraying the insanity in the character really well.

Their synergy was especially amazing at the last few episodes! I could feel the bond they have as police officers/investigators, the trust they have towards each other, which sparked into them risking their lives to save Hyun Jae and Ha Young in the last 2 episodes.

Wondering why I left rewatch value on one point? It has no rewatch value due to how good it is. You get so thrilled watching them solve crimes and identify perpetrators that it wouldn't be fun watching it again because you already know what's going to happen. This is the magic of good thrillers, your excitement and sense of wonder is sated to the point that trying to experience it again wouldn't feel as satisfying.