Synopsis: On his daughter's birthday, a middle-aged man, Dae-su Wu, is kidnapped and disappeared on his way home drunk by an unidentified man. He was imprisoned for no reason in a mysterious private prison. In vain, Wu Dae-su watches TV every day and eats fried dumplings for three meals. Through television, he learned that his wife has been killed, his daughter's whereabouts unknown, he is suspected of murder. In this regard, Oh Dae-su began to exercise, determined to revenge, and spent a long 15 years in prison.When Wu secretly dug through the wall, he was released one day to see the light of day. He desperately finds out why he was kidnapped and imprisoned, and embarks on a mad revenge plan…