In 1998, OH Dae-soo is drugged and kidnapped in front of his own house. Coming to, Dae-soo realizes he has been thrown into a private prison. The people who imprison him supply him with food, water and a television. Dae-soo watches the news and learns that his beloved wife was brutally murdered and the police suspects Dae-soo as the murderer. He vows to survive his ordeal and take revenge on the men who destroyed his happy life. Dae-soo habituates himself to the darkness in the cell, training his mind and body. He covers himself with tattoos, evidence of the time that he has spent in the cell. One day, Dae-soo is given sleeping gas again. He comes to and finds he has been released, 15 years after he was kidnapped. He tries to find out who is behind all of this and why.
