There is nothing bad I can say about this drama. Clearly Ji Chang Wook feels more comfortable with this type of genre and it shows because he left it all alone in this drama.

The plot seems simple, a police officer who is generally not afraid of anything, who at first finds himself obliged against his will in a leak in an association dedicated to drugs and all kinds of crimes.

But it is not as simple as it seems. The more Park Joon-mo is involved as an undercover, the more he has to do things, like kill, that he didn't dare to do at first. His vision of what is wrong and right begins to blur little by little. And that's because even though he was supposed to stop this entire drug trafficking network, he begins to take appreciation to Jung Ki. Somehow, upon learning his story, he begins to feel some sympathy towards Jung Ki even though he knows that what they are doing is totally wrong and bad.

The problem really begins when Park Joon-mo's wife interferes in the investigation.

He knows that Jung Ki was always in love with his wife, he feels jealous in this situation but he must maintain his composure, so that they do not suspect him, as if he did not know her and at the same time protect her.

What really bothered me was his wife's attitude. When they find themselves in a bloody fight where Park Joon-mo must protect his boss/friend Jung Ki and his wife. His wife looks at him as if he were seeing a monster. First, why do you meddle your husband's work knowing that he must do everything possible, even if it is not morally correct, to not be discovered. They had weapons of all kinds and her and Jung Ki's lives were in danger, what did you expect? What will a water gun use to defend them? However, it seems like he has no problem with what Jung Ki does. Here it clearly marks an inevitable end for them.

Park Joon-mo is not the same and his wife cannot conceive what Park Joon-mo does. Knowing that it is his job and he had to stay undercover as much as possible, because the members of Jung Ki's original gang had already begun to suspect him.

Clearly Jung Ki by committing suicide gets what he wants. Let no one be happy.

This is clearly seen in Park Joon-mo's promotion scene. I don't know if he's happy, he's furious. He lost his best friend and right hand man. What really for? Not at all. At this point for Park Joon-mo, nothing made sense anymore. He was disgusted with his own job and didn't give a shit about the promotion he got. At the end of it all, he was the one who had to get his hands dirty so that others wouldn't get them dirty. And that disgusts him.

He doesn't even look at his wife once and stays away from her. Everything that once brought them together is gone.

Clearly when he goes to Jung Ki's grave he leaves his wedding ring, which tells us that he has cut off all relations with his wife. I don't think they will get back together in the future.

Everything has changed. The two of them have changed and the love they felt for each other died. He knew it the moment he saw the face of his wife, who looked at him as if he were a monster.

At the end they let us see a small scene in which Park Joon-mo and Jung Ki smile genuinely. In the end, as mean and ambitious as Jung Ki was, they treated each other like brothers the entire time they were together.

Which leaves us reflecting that in life there is no black and white. Each person has their nuances, whether good or bad. Sometimes by doing our job we are corrupted, it is inevitable.

A Park Joon-mo who didn't dare kill anyone at first, is forced to start killing. And as we all know, when you cross that line, nothing about you will ever be the same again.

The action, the story, the performances and the OST was perfect.

There are no complaints for this drama. I honestly think it's the best drama Ji Chang Wook has done in his entire career. He is a very good actor, who can show you different facets. But without a doubt this type of genre is the one that suits him best.