After a number of people in a small town in Maine are killed by supernatural creatures lurking in a thick fog, a small group of survivors led by artist David Drayton (Thomas Jane) take shelter in a local supermarket.
The frightened survivors attempt to discover the origins of the deadly mist, with rumours pointing toward an experiment conducted at a nearby military base. As the world around them slowly descends into a literal hell-on-earth, one of the survivors calls for Old Testament-style sacrifices in order to pacify the malevolent forces.