制药公司小职员医学博士出身的宰赫(金明民 饰)早些年被弟弟宰弼(金烔完 饰)劝诱炒股,结果赔得精光,如今委身于一家毫无前景的制药公司做推销员,在外低声下气,看客户脸色行事,心中的郁结只有向家中妻儿宣泄。与此同时,汉江流域附近接连发现数十具尸体,死者全身皆如干尸,死状恐怖。这一事件波及甚广,连宰赫身边的人也无法幸免。经调查发现,死者体内无一例外寄居着本应存在于昆虫身上的铁线虫,铁线虫会刺激宿主食欲大增以吸收养分,等到繁殖期时令宿主神志不清,投水自杀,再进入水中大量繁殖。面对这一新型变种,人类束手无策,无计可施,死亡人数呈几何数增加,韩国上下乱作一团,有如末日。 原本为生计奔忙已焦头烂额的宰赫,该如何保护家人幸免于难……Jae-hyuk is an ordinary man in his 40s. He works as a medical supplies salesman and is hassled by doctors all day. His brother Jae-pil is a detective that is not all that interested in public safety and spends most of his time moaning about the stock market. The discovery of a series of floating, gruesomely skeletal bodies around the country sparks hysteria. The police commissioner is disturbed to see CCTV footage of people jumping into water as if they were possessed, and drowning themselves. Time passes and hundreds of similar cases are reported, leaving officials stumped as to the cause of the deaths. The government declares a national emergency. Jae-pil joins the massive investigation and meets the mayor of a small town who claims he witnessed several men in work uniforms dumping infected dogs into the streams and realizes that there is a conspiracy behind the outbreak. Meanwhile, Jae-hyuk's wife and children are showing the same symptoms as the victims, leading to a frantic search for medicine. Through Jae-pil he learns of a warehouse containing a potential cure in thousands and thousands of doses and heads there with no idea of what he's heading into.