just one word MASTERPIECE.
Sequence of events was so smooth. it built the pace of the drama in the first couple of episodes. and then smoothly integrated the first story to the main story of the drama. the plot twist was not expected at all. It was so satisfying ,and it made a lot of sense. the cast did amazing job. there should be more drama like this.
the best part about this drama for me is that there was no romance. don't get me wrong it is not like i don't like romance. however a lot of korean dramas put romance in the story when it so not needed. This make the drama lose its main point. thankfully this drama did not fall into this trap. instead it focused on the main story and built it step by step until the very end of the drama.