It's been four years since the zombie apocalypse devastated Busan. Seok-woo (played by Kang Ha-neul), a former soldier, has been surviving in a post-apocalyptic world. He receives a message from his sister, Soo-an (played by Kim Do-yoon), who has managed to find a truck filled with 20 billion won worth of gold. The catch - the gold is located in Busan, and Soo-an needs Seok-woo's help to retrieve it.