Marine Captain Jung-seok is driving his elder sister, her husband Chul-min and his nephew Dong-hwan to a ship leaving South Korea, which is being swept by a zombie outbreak. On the way, he encounters a family with a young child who needs a hitch, but he ignores the family’s pleas and drives away. In the cabin of the ship, an infected man turns into a zombie and infects numerous people, including Dong-hwan. Jung-seok then unwillingly decides to leave Dong-hwan and his mother behind and stops Chul-min, who returns after getting some supplies, from entering the cabin.
Empat tahun selepas peristiwa Train to Busan, seluruh Korea telah ditinggalkan, dan yang tinggal hanyalah geografi, zombi, dan keruntuhan Korea Selatan. Sekumpulan tentera laut dalam misi pencarian terperangkap di dalam dan mula menyaksikan sesuatu yang akan menguji nasib dunia.