I thoroughly enjoyed this drama. It met with things that I like: crime, fighting, mystery, thriller.

Although I barely like Korean thrillers because they miss the mark a lot for me, this type of thriller was OK.

I loved the cast. The chemistry wasn't strong but it wasn't weak either.

I said this contain spoilers because I had a few takeaways from this drama.

The main character was good at deciphering voices. That's how the series started. Then all of a sudden she could hear sounds but could never tell what it was. One episode had me saying 'what?' aloud because she could hear tapping on a cage hidden inside a cement wall but she couldn't hear footsteps coming right up behind her. That's how a few instances were in this series.

The main male lead was just angry throughout the whole series. I liked his fighting but he was just too angry. They should've called him 'angry dog' instead of 'crazy dog'.

The main villain....boy did they do too many closeups of his eyeball, mouth, hands....I'm thinking is the thriller part they were talking about? He was creepy I get that but at some points I really wanted him to just die already. Plus the clicking of the teeth from the two bad guys hurt my ears.

I don't know how I felt about the last episode. I did like how it went off. I guess I'm just impatient with how Korea wrap up the very last episode of their dramas. They either get it right or the majority of the time they get it wrong. Plus the first 40 minutes were drawn out and then in the end they just talked about how the other scenarios ended for the other bad guys.

I'm glad there's four seasons to this. Korea barely make sequels so when I saw there were three more series I feel compelled to watch. This time I feel like I'm being spoiled at this point.