Four years after the events of Train to Busan, soldier Jung-seok (Gang Dong-won) is assigned a covert operation. He leads a group of soldiers on a search and rescue mission to find survivors, and to retrieve a huge bag of cash. However, not only does his team come across a large pack of zombies, but they also discover that post-apocalyptic survivors have turned into the worst by pitting humans against zombies in a cage match.

The lives of Jung-seok and his team will depend on whether the best — or worst — of human nature prevails in the direst of circumstances.