On his daughter's birthday, middle-aged man Wu Daxiu (played by Choi Min-sik) is kidnapped by unidentified individuals while on his way home drunk. He finds himself inexplicably imprisoned in a mysterious private prison. Despite attempts to end his life, Wu Daxiu spends his days watching TV and eating fried dumplings for every meal. Through the television, he learns that his wife has been murdered, his daughter is missing, and he is suspected of being the killer. Determined to take revenge, Wu Daxiu begins to work out and endures a long 15 years in captivity. When Wu secretly digs through the wall, he is released one day and sees the outside world again. He desperately searches for the reasons behind his kidnapping and embarks on a crazy revenge plan. He meets a young sushi waitress (played by Kang Hye-jung) and, with the help of his old school friend, tracks down his enemies, punishing the prison guard (played by Oh Dal-soo) in the process. Meanwhile, the mastermind enemy Li Youzhen (played by Yoo Ji-tae) also comes to light...