After a drunken night on the town, an ordinary Seoul businessman, OH Dae-su, wakes up in the morning to discover he has been locked up without explanation in a mysterious prison. After fifteen years, Dae-su suddenly and inexplicably finds himself freed. A voice on a cellphone taunts him into discovering who kept him imprisoned. Dae-su plunges into a world of competing vengeance, his own drive for revenge matched by the equally implacable and Byzantine...

A high school student, Min-ah, finds a diary that can cause hallucinations. It belongs to two of her fellow students. After one of them commits suicide, Min-ah feels as if she is possessed by the dead girl.