I was waiting for this drama, mainly because of Yoo Ah In, and he did not disappoint. I have never seen manga, so the plot was completely unknown, and acetal the storyline was interesting.
There are several actors who can play good and bad guys, and Yoo Ah In definitely nailed his role here. A handsome charismatic pshycopath leading a cult and he played all sides of the character very good. May Hollywood borrow him? I have not seen good villains in western cinematography for ages.

Also Ryu Kyung Soo, I have seen him Before playing More playful and funny characters, here he is a bad guy
and he acted him so well. I hope he get more recognition.

However, I feel like the script did not do enough for the characters. Killing the main lead after two episodes? We don’t even know what kind of a man he was, a little background history would be great.
It felt a little rushed, and a lot of stories are incomplete. This could have been 10 episode series easily, with more detailed script. The first episode was slow, and than after second episode everything escalated so quickly, and became confusing. Where are cop and his daughter? What happened to children of lady from second episode? How the Soda loan firm was formed? How did the MFL survived?

The ending is a cliffhanger, and it looks like they are leaving the rest for season 2. But I am not sure if they will do the second season? If not than my rating will definitely decrease.

Overall, I am not regretting watching it. I like thrillers, and I enjoyed the story and idea, I enjoyed acting and the cinematography. However, I don’t think I will rewatch it. It reminded me of a “sweet home” and I rewatched “sweet home” couple of times, but this one is not that exciting and complete.
Also I am Not sure if that’s a horror genre that would make you scared. “Save me” was way more traumatising and creepy when representing a cult.
There is a lot of blood and people dying, but I think all Korean criminal dramas are like this. Mouse was way more bloody and creepy. So I would say that series was not very scary, but if you are a softhearted person, who can’t watch people dying and blood, than better skip this one.

I am giving 9 just for Yoo Ah In and his acting. If not for him, than the score would be 7 at most.