When a mysterious monster rises from the Mekong River and attacked Bueng Kan, cuts off people 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.

Treachery centers on a man (Biehn) who is reunited with his estranged son at a remote wedding party. When a storm strands the party, ugly truths are revealed.