This is the most action-packed K-Drama that I have seen. I hate to give it a lower rating, which I did, but no fault of the actors. Both lead actors. Park Shin-hye and Cho Seung-woo did fantastic in their rolls - Park Shin-hye in the action packed gun scenes and Cho Seung-woo in his portrayal of the smartest man in the world - a computer coding genius and CEO. The lower rating is for the writers as it was confusing - are we now in the present, past or in the future? The ending is extremely confusing and if you have to go online to get an explanation and then find no one else gives a proper explanation either, then the writer hasn't done their job. I also don't care for writers that include story lines about nuclear war either as some of us are old enough to remember the fear we felt during the Bay of Pigs incident when we were told we weren't going to wake up in the morning. To use it for a movie theme I don't think is right and the word never used to be even uttered and now movies are made for entertainment. So All my stars go to the actors who did a great job and those who did the fantastic filming in the show - I am sure it was extremely difficult.