Have you heard of a place called Mong where the dream world intersects with the real world? At Mong, rules are easily bent and intuition often overwhelms logic. Desires go out of control and wishes come true in wrong ways. Once captured, monsters and villains from Mong are sent to the prison of Nightmare. A hideous serial killer manages to break out of the jail into the real world, terrifying the earthlings.

A reporter from an obscure magazine company hunts the killer doggedly. Or is it the other way around? He has to find the clues about the killer before his girlfriend becomes the next victim. Time is dashing forward. In desperation, the reporter decides to cross the border of no return and climbs down into Mong. Little did he know what's waiting for him at that murky place.