It's a little hard to follow, jumping from one parallel universe to the next. Nonetheless, I have to keep watching because Lee Min Ho is compelling as usual, and the other characters add to the suspense without missing a beat. I also have to keep watching just to make sure I have figured out all of the elements / characters correctly. It's a very cool concept, as I like science fiction, but it is not the typical K-drama to which we may have become accustomed during the 'stay-at-order'. But that kind of makes it more fun!