The plot goes nowhere. What caused the earthquake? What is the mad scientists backstory? What does the serum actually do? How does it work? What are the main characters relations and how do they meet? etc. I could line up many more unanswered questions. The glimpses of any sort of backstory were directly told to us in an unnatural placing, and what wasn’t told to us is left to for us to guess with much uncertainty. I watched this for Ma Dong-Seok and was left disappointed as his character was so terribly written I somehow managed to dislike him despite the writers attempts to make him the righteous, unbreakable character.