This a drama that delves into themes of corruption, greed, bribery, selfishness, and what kind of system these things produce.

What I loved most:

... regarding the story:
* I loved the characters -- except for a few of them who were hopelessly inhuman in their emotions, all characters have strengths and weaknesses to them. These are not always explored into the minute details but very much obviously there. The characters feel like people.
* All fights for the truth, all struggles for justice are not 100% successful. This is not a fairy tale, where the good guys win and all the bad guys are punished. The system stays firmly in place. Maybe some have learned a lesson, but not all of them.
* And still, things are looking up, at least in the personal lives of the "good" side. There's hope, as long as we are living.

... regarding the technical side:
* The actors are amazing! Facial expressions, body language, all perfectly controlled -- especially hard for the more multi-faceted characters.
* Loved that we get to see the progress of time via the background nature. We start in the bleak winter days and end at early summer -- I wonder if this is accidental or if we may read it as metaphorical.

... regarding the rest:
* No romance! Always a plus for me. Yes, there are two or three scenes, in which there are interactions which could be seen as light flirting or something, and once some short and good-natured heckling, but all of them can be easily ignored and nothing is ever openly acknowledged.
* For a S.Korean crime drama, there are astonishingly few scenes of senseless or exaggerated violence. There is violence, of course, but it always serves the plot in its intensity.

Recommended!