Plot
A zombie outbreak overwhelms South Korea, prompting international evacuations before the peninsula is quarantined in Busan. ROKMC officer Jung-seok drives his sister, her husband Chul-min, and their young son Dong-hwan to an evacuation ship. They encounter a distressed couple with a young daughter begging for a ride, but Jung-seok refuses to help them after noticing the husband is bleeding. On board the ship, an infected passenger turns into a zombie and bites several others, including Dong-hwan. Jung-seok's sister stays behind with her son and is bitten; Jung-seok seals off the cabin to contain the outbreak, preventing Chul-min from entering as armed soldiers intervene.
Four years later in Hong Kong, Jung-seok, Chul-min, and two other Korean refugees are recruited by Chinese mobsters to return to South Korea and retrieve a truck containing US$20 million. In exchange, they are promised half the money. The team arrives at night, locates the truck, and kills the zombie driver. The noise attracts nearby zombies, but the team manages to escape with the vehicle.
While heading toward Incheon Port, the team is ambushed by a rogue militia squad of Unit 631, led by Sergeant Hwang. Their vehicles crash; one team member dies in the accident and another is killed by Hwang. Chul-min hides in the truck while Jung-seok flees on foot. He is rescued by two sisters: skilled driver Joon-yi and the younger Yu-jin. They bring him to their hideout, where they live with their mother Min-jung and grandfather Elder Kim, who believes that his military friend, Jane, would receive his radio transmission and rescue them. Jung-seok realizes that Min-jung and Yu-jin are the mother and young daughter he had refused to help four years ago.
The militia transports the truck to their base, unaware of the money inside. They imprison Chul-min and forces him to participate in a survival game that pit captives against zombies. Private Kim discovers the money and informs Captain Seo, who secretly contacts the mobsters and plans to escape the peninsula alone with the truck. Meanwhile, Jung-seok tells Min-jung and her family that an extraction ship awaits his team and the truck at Incheon Port. Min-jung devises a plan to steal the truck and escape the peninsula with her family and Jung-seok.
The following night, Jung-seok and Min-jung infiltrate the militia base. Holding Private Kim at gunpoint, Jung-seok learns that Chul-min is still alive, and halts the ongoing survival game to rescue him. Chul-min narrowly saves Jung-seok from a zombie bite but is shot dead by Hwang. Min-jung fends off Seo and escapes in the truck with Jung-seok, but their route is blocked by a horde of zombies. Joon-yi, Yu-jin, and Elder Kim arrive and distract the zombies with their car.
The two vehicles escape with Hwang and Unit 631 in pursuit. They manage to destroy the pursuing vehicles, and Hwang is killed by zombies. Seo, having killed Private Kim, ambushes the family at Incheon Port and takes Joon-yi hostage. Yu-jin distracts Seo, allowing Joon-yi to escape, but Elder Kim is fatally shot and Min-jung is wounded in the ensuing confrontation. Seo escapes with the truck and boards the extraction ship, but the mobsters betray and shoot him. As he dies, Seo reverses the truck to deliberately jam the cargo ramp, allowing zombies outside to overrun the ship and kill everyone on board.
Jung-seok and the family manage to signal a passing U.N. Chinook, who responded to Elder Kim's radio transmission. Min-jung, injured, stays to hold back a horde of zombies so Jung-seok and her daughters can reach the helicopter before preparing to shoot herself. Remembering Chul-min's words about his failure to protect his family, Jung-seok returns to save her and shoots the zombies down. Min-jung escapes, and the family safely board the helicopter and evacuate the peninsula.
