Jae-hyuk is a pharmaceutical worker for a medical supplies company. When a series of dead bodies are found floating in the Han River. The public is shocked to discovered that the deaths are related to a fatal outbreak of virus-infected mutant parasitic horsehair worms, called ‘Yeongasi’, that can control the human brain. Those infected shows symptoms of hunger and thirst, hence jumps into the river to combat dehydration. Whilst the authorities work to find a cure, Jae-hyuk struggles to save his family when they also exhibits similar symptoms.


Hae Gook (Park Hae Il) travels to a reclusive village to attend his father’s funeral. He wants to find out the reason behind his father’s strange death, but the villagers, in particular village chief Cheon (Jung Jae Young), seem to be watching his every move and eager to see him leave. Determined to get to the bottom of the mystery, Hae Gook enlists the help of prosecutor Park (Yoo Jun Sang) to slowly unravel the village’s sinister secrets.