If you have decided to watch this drama, be prepared for a fantastic thrilling story of people who are deeply flawed and dangerous, but who promise you an adventure from which, you will not want to come back to the real world. What do you say to a team, consisting of a detective who has been removed from the office for his personality and morale, a convicted gangster, who once organised the taking of whole Seoul streets, convicted contract killer, whose method is to kill and make it look as an accident, and he is in the prison only because he came and turned himself in... (WHY?) and a serial killer, who is a psychopath and a genius and insists he does not remember killing anybody, though his girlfriend claims he also tried to kill her... (another piece of puzzle you will have to watch the drama to understand) trying to solve complicated cases (like a serial murder case, an organisation that sells people and human organs, gangsters, drug dealers...) and working as a team to make their time in prison shorter, that is the reason you are given in the beginning, but as the story goes on, you start realising that every one of them has another reason for joining the team. Although they are pictured as cruel murderers in the beginning, you realise they are human beings who want 2nd chance, to be better, to be forgiven, to find themselves, to be humane! Sounds intriguing, doesn't it? Believe me when I say, that watching it will not give you even the chance to breath calmly! There were moments, where I had to stop the drama, have moment and then continue. This drama will have you imprisoned until you finish it and even longer, as after you finish it, you will have to talk to somebody and tell them how utterly fascinated you are with it. It is really rare in a drama, where there are no scenes that could be absent and you would not care, scenes that you can just fast forward through and get the story all the same, well, hear my warning, this drama has no such scenes, miss a second, and you will miss an important part of information, that you should have heard! I don't even think I have the right to talk about the actors, as every single one of them were brilliant in their role, Park HaeJin making me shiver with the twitch of his lips, Ma DongSeok and Jo DongHyeok (my first time seeing him) with their bromance, their heart and brain, Kim SangJoong, with his grief and anger, I don't find another word, except for... PERFECT! This is a gem, which I will recommend you every one who asks an opinion from now on.