very slick well written and planned and well-acted thriller with plenty of action like the best K-drama of its genre〜the concept is not that original but it is well done 〜reminds me of 「Mission Impossible」except it is not one completed story for every episode but leaves cliffhanger and there emerges an underlying backstory and plan behind the targeted individuals〜 you have to focus to follow the detail 〜this is binge watch quality which is rare for me。Great cast both main and support。 you really want them to get those low-lifes in high places。Song Seung Hyeon was also in similar genre「 Black」（also with Kim Won Hae） and 「Time Slip Dr Jin」 that I liked but his main career roles seem romance or melodrama〜Kim Won Hae also has a long distinguished career in similar roles （main and support） such as 「Nine Times Time Travel」、「Black」「 I am Human Too」 「Hotel del Luna」 to name a few it would have been good to see a follow up with these actors as they developed good chemistry。