Peninsula takes place four years after Train to Busan as the characters fight to escape the land that is in ruins due to an unprecedented disaster.

Since she was young, Soo-Nam has been able to do anything well with her hands. She holds 14 different certificates for typing excellence, but a computer takes over her job. Luckily, she finds a new job and marries. Soo-Nam and her husband decide to buy a house. They take out a loan to pay for their home. Soo-Nam works hard to pay off the loan, but she falls into more debt. Then ... an opportunity arises to pay off all her debts at once.

During the Japanese colonial era, roughly 400 Korean people, who were forced onto Battleship Island ("Hashima Island") to mine for coal, attempt to escape.

The film mainly follows the famous 1597 Battle of Myeongryang during the Japanese invasion of Korea (1592-1598), where the iconic Joseon admiral Yi Sun-sin managed to destroy a total of 31 of 133 Japanese warships with only 13 ships remaining in his command. The battle, which took place in the Myeongryang Strait off the southwest coast of the Korean Peninsula, is considered one of the greatest victories of Yi. Written by Anonymous

16-year-old Jang Ji-Gu (Seo Young-Joo) takes care of his ill grandfather, while he hangs out with other troubled kids. He was abandoned by his parents at an early age. After another run in with the law, Jang Ji-Gu is sent to a detention center. One day, Jang Ji-Gu hears that his mother Hyo-Seung (Lee Jung-Hyun) has come for him at the detention center. Hyo-Seung had Jang Ji-Gu at the age of 17 and gave him up soon after birth. Can they repair their relationship? Written by luraz isketambola