Season 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 sinkhol…

The news of the sinkhole spreads throughout Muji and more people come to look. However, things go wrong as they get infected by the black smoke and start attacking each other. Not knowing how it is triggered, but a larg…