Republic of Korea Marine Corps Captain Jung-Seok is driving his elder sister, his nephew Dong-Hwan, and his brother-in-law Chul-min to a ship to escape a zombie outbreak in South Korea. On the way, he encounters a family with a young child, but he ignores the family's pleas for help and keeps driving. Later, in the cabin of the ship, an infected man turns into a zombie and infects numerous people, including Dong-Hwan. Jung-Seok's sister refuses to leave her son, so Jung-Seok is forced to block everyone, including Chul-min, from accessing the cabin.

Four years later in Hong Kong, a guilt-ridden Jung-Seok and Chul-min are recruited by Chinese mobsters for a mission with two other Koreans to return to the quarantined peninsula and retrieve an abandoned food truck which contains US$20 million in bags; if successful, they would receive a split of half of the money. The team arrives at the peninsula at night by boat and soon find the truck. They escape with the truck as zombies began chasing them.

On the way back to Incheon Port, they are ambushed by a rogue militia Unit 631, led by Sergeant Hwang. Jung-Seok is thrown out of the truck and Chul-min hides inside. The two other members of the team are killed, one as a result of the crash, and one by Sergeant Hwang. Jung-Seok is rescued by two sisters: Joon and her younger sister Yu-Jin. Joon drives to a hideout where the children live with their grandfather Elder Kim and mother Min-Jung - the latter, Jung-Seok realizes, who is the lady who pleaded for his help four years ago.

Meanwhile, the Unit 631 soldiers take the truck to their compound and imprison Chul-min upon discovering him in the back, forcing him to take part in a series of timed survival games between prisoners and the infected. Private Kim and Captain Seo discover the cash in the truck and secretly hatch a plan to escape the peninsula with the truck, keeping their plans a secret from Sgt. Hwang and the rest. Meanwhile, Min-Jung learns from Jung-Seok that there is a ship at Incheon Port waiting to extract him and the truck. She decides to steal the truck from the compound so that the five of them (her family and Jung-Seok) can escape.

The following evening, near Unit 631's compound, as Joon, Yu-jin, and Elder Kim wait in the car, Jung-seok and Min-jung sneak inside, where they discover the truck and encounter Private Kim. While holding Private Kim at gunpoint, Jung-seok learns that Chul-min is alive in the compound and goes to rescue him. He almost succeeds, but Chul-min is killed by Hwang while saving Jung-seok from being shot. Jung-Seok is saved by Min-jung, and the two escape the compound with the truck. Numerous Unit 631 soldiers, led by Hwang, give chase in their vehicles; Captain Seo, failing to commandeer the truck, shoots Private Kim dead and pursues the group separately in another vehicle. In the ensuing chase, Jung-Seok deliberately shoots and shatters a glass tunnel, freeing the horde of zombies inside, which overwhelm Hwang's vehicle.

The five reach Incheon Port when Seo rams his vehicle into Joon's car, then holds her at gunpoint. Yu-jin manages to distract Seo enough to allow Joon to escape, but he shoots Elder Kim as the latter tries to protect Yu-jin. Min-jung promptly attempts to shoot Seo, but is shot in the leg. Seo flees with the truck and drives into the cargo hold of the ship, but he is betrayed and shot by the mobsters, who had no intention of honoring the deal to begin with. As he dies, Seo reverses the truck to prevent the cargo hold's gate from closing, which allows the zombies outside to enter and kill everyone inside the ship.

After Elder Kim dies from his wounds, the remaining four spot a United Nations CH-47 (Chinook) helicopter flown by Malaysian UN troops and draw its attention. An injured Min-jung requests that Jung-Seok bring Joon and Yu-jin to the helicopter, while she clears the path of zombies. Min-jung then traps herself in a truck and presses on the horn repeatedly, intending to attract the zombies to her so that the three others can escape. Recalling an angry claim Chul-min made in Hong Kong that Jung-seok did not do his best to save their family four years ago, Jung-seok rescues Min-jung by dispatching some of the zombies that have trapped her in the truck. She quickly makes the run to the helicopter, while Jung-seok covers for her by shooting the zombie horde. The four board the helicopter and escape the peninsula.

https://en.wikipedia.org/wiki/Peninsula_(film)
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