After a violent storm attacks a town in Maine, an approaching cloud of mist appears the next morning. As the mist quickly envelops the area, a group of people get trapped in a local grocery store. The people soon discover that within the mist lives numerous species of horrific, unworldly creatures that entered through an inter-dimensional rift, which may or may not have been caused by a nearby military base. As the world around them manifests into a literal hell-on-earth, the horrified citizens try desperately to survive this apocalyptic disaster.