the storyline was very great, I was hooked since the first episode till the very end. It keep my tense up and very thrilling every single episode. the drama is kinda dark too giving more thrill. There wasn't a time that I feel like it was draggy. I was curious and eager to know what happen next and after all of those, the revelation of the truth and the way they solved it was so satisfying. I found this drama because of seung yoon and se young, yet I fell in love with all the casts, great acting indeed. just make sure you focus and remember what happen at each timeline, so you won't get confused. love love love!!!