Illegal disposal of toxic liquids into the river Han becomes horrible destiny for countless Koreans some years later.

Once more slightly mentally retarded Gang-du sleeps in the kiosk on the bank of the river Han and waits for his teenage daughter Hyun-seo. Before the stunned crowd understands, a giant monster jumps up from the river and is after them. One of the victims which are torn into the depth is Hyun-seo. Authorities quickly declare a state of emergency, the river basin is blocked off and the survivors of the attack are interned. Among them bewildered Gang-du. Suddenly, his mobile phone rings, and he hears a cry for help of his daughter presumed dead! She was abducted to a sewer.

Gang-du sets off together with his alcoholic brother Nam-il, his sister Nam-joo, most famous sports archer of Korea, and his father to find the girl. The family is pursued by the police which prepares a poison gas operation with the help of the US military.

Meanwhile Hyun-seo and a little boy whose older brother was killed by the monster desperately fight in the sewer for survival. However, after the brave family gets rid of the monster with gasoline and a burning arrow, only one of both children survives. (by Gerhard)