In the early morning of September 6, Park Eun-min boarded the KTX406 high-speed train bound for Busan with other passengers. No one noticed that a woman who acted strangely entered the car. Everyone was doing their own things in an orderly manner. At this time, the woman who hurriedly got on the bus fainted, suddenly climbed on the flight attendant's back and bit the flight attendant. In an instant, the bitten flight attendant had the virus spread throughout his body and became a brutal infected person. The rampant virus continued to spread and infected people emerged like a flood. Everyone on the train fought back hard. Just when the infected people attacked Park Eun-min, a surgeon named Jin rescued her. As the survivors continued to move, the two fell in love during the difficult process of escaping.