The worst epidemic ever seen is sweeping through Bundang, the suburb of Seoul. After smuggling illegal immigrants into the country, Byung-woo dies from an unknown virus. Soon after that, the same symptoms are plaguing scores of residents in Bundang. People are helpless against the airborne disease and the number of infected increases quickly, spreading chaos. As the worst-case scenario precaution, the city of half a million people, just 19 kilometers from Seoul, is about to be sealed off. The government orders a complete shutdown. Meanwhile, infectious disease specialist In-hye and rescue worker Ji-goo go into the closed city to find the blood serum of the index case, a crucial part of developing the vaccine.
一群东南亚偷渡客历经艰险来到韩国，但是整个集装箱内的偷渡客几乎全部死亡，只有一人拖着羸弱的身体侥幸逃入闹市之中。殊不知此人身上携带致命猪流感病毒，短短一天时间，病毒迅速蔓延城市的各个角落。许多人在不知不觉间被感染，进而将死亡的阴影引向周围所有的人。美丽的女医生金仁海（秀爱 饰）是一位单身妈妈，她不久前遭遇一场车祸，幸被消防队救援人员姜智久（张赫 饰）救出，却因丢失重要论文资料而备受上司苛责。值此期间，韩国蛇头的弟弟因流感送入仁海的医院治疗，经诊断终于发现流感的起因，死尸横陈的集装箱无疑成为查找病源的关键。 未过多久，猪流感病毒成几何式爆发蔓延，坐享太平的民众面临前所未有的灾难…