Gang O Su became a detective because of an event in his past. One day he receives a strange tarot card in the mail. He ignores it, but soon after somebody he knows dies. Another tarot card arrives, and he decides to look into it before somebody else is hurt. Determined to find the manipulator of the incidents, he seeks help from Hae In, a woman with Token object reading ability.
As far as Revenge dramas go this is one of the best - anyone who has ever read the Manga (or watched the Anime) "Monster" would probably appreciate this to a good degree. The way people are manipulated in order to carry out someone else's intentions are meticulously and perfectly executed. Every single move has been calculated and every single person in play has been carefully chosen - this is why the series does justice to how the characters are used - there are quite a few of them yet no one truly gets tossed aside and forgotten.
I see people commenting about the blankness of O Seung Ha and that makes me just shake my head. O Seung Ha was as perfect a character as his character needed to be (anything more would have been too much and just killed the whole thing as it would have been excessive). He was far from blank, he was consumed, the man was practically a second away from internally combusting and I found it so amazing how he conveyed every single thing with his eyes, there were scenes I had to pause and go back to just so that I could look at his facial expressions - those eyes..at times one eye would show you his complete intention while the other was as normal and stoic as ever, then gradually throughout the series you saw how more and more intense, the look in that eye would become and eventually seep into the other (and if you think that was it..nah...whenever he let his guard down you saw a whole other side of him that revealed a completely different person). This is why I mentioned the Manga/Anime "Monster" [spoiler] O Seung Ha isn't as inhuman as Johann, but the way they appear to people vs how they are inside, how meticulous they are, and how they manipulate others is close enough[/spoiler].
Anyway, I think its definitely a drama that no review can give justice to simple because of how viewers may interpret O Seung Ha and Gang O Su.