Absolute blockbuster I would say. I would love to meet writer Park one day. And the cast was chosen perfectly. It's a perfect choice if you are into mystery, suspense, psychology dramas. Even if you are not, this is a must watch. It gave me chills sometimes. It felt as if I was in the drama, shouting at my screen for help๐๐. All the OSTs and background music fit in so well. Godddd, I could write volumes about how much I love this drama. And I regret not watching it early :'(