Blood Rain tells the story of a slew of grisly murders plaguing a small, fairly isolated island village. However, it's not just the mounting death toll that's causing residents to worry, but the sadistic, methodical way in which the victims were killed. With the killer still on the loose, the government sends in special investigator Wong Gyu (Cha Seung Won) to crack the case. While conducting his dogged investigation, he soon uncovers a myriad of hidden secrets, tracing the murders back to an incident that occurred some seven years earlier. The previous owner of the village's paper mill was executed as a Christian. Does that mean that the murdered man's spirit has come back to seek bloody retribution? The real truth, Wong Gyu learns, may be far more terrifying...