Dark Hole Season 1 Episode 1

After losing her husband to serial killer Lee Soo Yeon, police detective Lee Hwa Sun makes her way to Muji city in order to bring the murderer in. But unlike what she is hoping to find, she runs into an enormous sinkhole in the middle of the mountains. Black smoke arises from this mysterious sinkhole and the people of Muji are left clueless about what it is.