A group of immigrants are smuggled inside a shipping container with their final destination being South Korea. Inside the container, one of the immigrants is a carrier for a lethal and highly contagious virus. Byung-Ki (Lee Hee-Joon) and Byoung-Woo (Lee Sang-Yeob) drive to the shipping container to release the immigrants. They soon discover that all of the immigrants are dead, except for one man. Soon, thousands of people become infected every hour by the deadly virus, which kills within 36 hours of infection. The entire suburb of Bundang is quarantined by the government in a desperate attempt to stop the virus from spreading further. Firefighter Kang Ji-Koo (Jang Hyuk) is one of those quarantined. Dr. Kim In-Hae (Soo-Ae) is one of the first responders to the outbreak of the virus. The outbreak becomes even more personal once she suspects her own daughter (Park Min-Ha) is infected by the virus. Firefighter Kang Ji-Koo and Dr. Kim In-Hae frantically work together in a race against time to find a cure.