Well, this drama is one of the best mysteries you can ever watch! every time you think you know who the suspect is, you end up having doubts about someone else instead. until the last moment you never really know who it may be! I have go to say my most favourite character has got to be Jung Ha Yoon, others may not agree but that is just my opinion (if I say why it will only lead to spoilers). The only reason I gave the story line a 9/10 was because even in the second series their backgrounds, or any type of mystery cases were not related to the characters in any way(apart from the main character which kind of got annoying after a while, but then again that is just my personal opinion). BUT watch the drama I definitely recommend it,even when I was creeped out/scared the most I still wanted to carry on watching because it was soo interesting and captivating.