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 South Korean man bumps into a former, but forgotten childhood classmate one day and he hits it off with the young woman. An immediate romantic tryst follows, but the young woman plans to leave for Africa in a few days. She asks her rediscovered friend to feed her cat while she is away. He does so and is eager for his new romantic interest to return. The situation quickly becomes complicated, however, when she returns from Africa with a mystery man...