This drama is very much like you are watching the variety show "Who's the Murderer".

The plot, characters, and lines are really thought well. Especially how the story goes. When you are watching, you will actually tend to try to solve the mystery together with the characters. It's interesting how they actually film this whole drama in just one building (just like how they did in the variety show), in fact, they made use of each room. I also like how they actually added some funny lines to ease the tension.

The OST and the short clips make the drama a little scary but totally match the whole drama. I must say there was an episode where the editing of the video was done badly, I'm not sure if it was due to filming the scene in different angles and different lines but overall one of the best detective dramas I've watched.

For all those that want to watch it, the drama has yet to come out with eng subs yet.