It starts off with a deer getting hit by a truck in a biochemical zone, and soon after the truck drives off, the deer comes back to life with an ill look and runs off. This is the first major turning point in the film. Seok-woo (played by Gong Yoo) is the father of Soo-an (played by Kim Su-an). He may not be the best father to her, but he tries his best to make ends meet. He decides to do the one thing she’s been asking for; a trip to Busan to see her mother. As all the passengers board the train and get comfortable, the train ride takes an unexpected turn for the worst. As panic ensues among the passengers, they are forced to adapt and survive the new, adrenaline-rushing circumstances. A game of “survival of the fittest”.