I had to take a couple of days to process my thoughts before writing this review. I have never been so affected by a drama before in my life, and honestly I don't know if my longing for this drama is something I'd ever care to repeat. I started this hoping for action and serious topics. I wanted plot and not romantic shenanigans. The drama starts off being pretty much all about a cop looking for his kidnapped daughter. This guy, however, is far from likable, and I found it difficult to sympathize with him in his plight. Why? Because he was, to put it simply, crazy, violent, and screaming. Lots of screaming. Lots of swearing. Lots of beating up suspects without evidence, heavy police brutality. This dude cared for nothing and no one but his daughter and wouldn't hesitate to brutally assault anyone he perceived to be in his way. That's where Clone #1, Sung Joon, comes in. Don't worry, I won't spoil anything. He has no memory of who he is, but Chief Jang decides poor Sung Joon is the key to finding his daughter. When these two meet, this is when the story really kicks off. I hated the detective for the first 2 episodes, but he does become more tolerable thanks to Sung Joon, who is kind and warm and patient where Chief Jang is crass, rude, and prone to fits of random rage. So for the first part of the drama, I watched because I was invested in the development between Jang and Sung Joon. I thought they were a great pair and really balanced each other nicely, and I'm a sucker for any kind of non-romance relationship focus. Chief Jang treated Sung Joon like a tool at first and didn't see him as a human being at all, and I wanted to see that change. There was some mystery and plenty of action for the first 6 episodes, but then it slows down and becomes mostly just drama and mystery with action sprinkled in. Eventually, the plot moves away from the father-daughter focus and we realize that ultimately this is a story about two clones. It's a sad story. Don't watch this if you don't want a ride on the rollercoaster of emotions. One clone is "evil," selfish and out for revenge and the other is kind, selfless and willing to put his life on the line to help near-strangers. But the characters are not simple, and evil clone is not actually just an "evil clone," but is a deep, complex character that will remain in my mind pretty much forever. What is the story really about? It's about clones learning to be human. It's about a father and his daughter. There's also an evil dude who wants to cure his illness and there's his evil spawn who aren't really worth mentioning but the story isn't really about them. No romance, just friendships and family relationships. Yay! Without Yang Se Jong, this drama would be nothing. His portrayal of three characters is something you really have to see for yourself. But let's say I had to keep reminding myself that it was the same actor. He brought the clones to life in a way that made me feel like I personally knew them. The other actors are good too. And JJY is so much more tolerable when he's not screaming his head off. It's not a perfect story, and there are aspects I wish had been different (more interactions between the clones, more father-son bonding with Jang and Sung Joon, less of the secondary cop characters), but these factors don't change my love for this drama. I can't stop thinking about it and have already rewatched most of it 2-3 times.