When a mysterious monster rises from the Mekong River and attacks Bueng Kan, it cuts people off from the outside world. Officials and people in the area, including Chinese scientists who accidentally came to conduct research in Thailand, all forces must be mobilized to catch this crazy monster before it’s too late.

A young couple go for a picnic beside a lake in the grounds of an empty house. Three years before, the owner had murdered all his family, killed his animals and disappeared.