At the break of dawn on Tancheon road, a gruesome corps of just skin and bones is found. Soon after, there are dead bodies everywhere wherever there is water and Korea is plunged into a state of complete chaos. With a short incubation period and 100% fatality rate, a parasitic mutant brainwashes its human hosts to find water and kill themselves, and the number of infected is growing out of control. To contain the situation, the government sets up an emergency response center and quarantines the infectees. Jae-hyuk is a busy salesman at a pharmaceutical company. While he was busy with work, his wife and children are infected by the mutant hairworm, and he struggles to find a cure for his family. In the midst of disaster, Jae-hyuk’s brother Jae-pil, who has been investigating a strange case of mass deaths, finds a lead on the mutant hairworm chaos, and two brothers dig out the truth.