Seoul was engulfed in a series of mysterious outbreaks of an unknown virus, against which medicine was powerless, due to which the authorities declared a state of emergency. The high-speed train to Busan became a kind of shelter for those lucky enough to get out of the dangerous city. None of the passengers even knew that they were lucky to get a ticket, since it was he who could save their lives. But how long can people stay safe? The ruthless virus spreads with great speed and at some point it can overtake passengers. Will anyone be able to save their lives and get out of the train? ..