Shi Yu (Gong Yoo), a fund manager at a securities company, is bright and capable, but he is also a person who values profit over righteousness. His wife broke up with him for this, and his daughter Xiu'an (Kim Xiu'an) became more and more disappointed with such a selfish father and decided to go to Busan to live with her mother. On Xiu'an's birthday, Shi Yu took time to accompany his daughter on the express train to Busan. At the same time, extremely suspicious riots occurred all over the city. The government tried its best to whitewash the fact that it could not cover up the rampant zombies, and even the ignorant train passengers fell into a hell of panic and despair because of the arrival of uninvited guests. At the moment of driving, an infected person rushed into the carriage, and she quickly turned into a corpse and launched a bloody massacre of healthy people within her sight. Before long, the number of zombies exploded geometrically. Shi Yu was forced to struggle to survive in a cramped space with the survivors. The long journey to Busan is full of murderous intentions, and the humanity of each survivor is also under great test in times of crisis...