Based on a novella by Stephen King, I can only admire the simplicity of the concept: after a storm, a New England town finds a dense, white fog rolling towards them. The people who happen to be in the local supermarket are startled by the arrival of a local, proclaiming that "something" in the mist took his friend. Startlement turns to fear when they discover the veracity of the claim, and that they are now basically under siege. Local artist David Drayton (Jane) takes command of one section, but he is countered by Mrs. Carmody (Harden), the local religious loony, who insists that this is the wrath of God, and a precursor to the ends of days. As an increasingly-bizarre array of creatures attack the supermarket and its inhabitants, her world-view grows increasingly powerful among the frightened inhabitants, and she demands sacrifices to appease the monsters outside. Drayton is left, along with the saner members of her 'congregation', to decide whether it might be safer to take their chances in the unseen world beyond the supermarket doors.
It's interesting to contrast the approach here to the subtler approach favoured in something like The Haunting. Darabont could easily have left everything completely unseen in the mist - after all, King went into little detail about them in the original story. However, he seasons the sense of dread resulting from the situation, with some impressive monsters created by KNB: the "WTF is that?" moments which result only enhance the terror, since it's proof that whatever is out there, is indeed stranger and more horrible than you can imagine. This is special effects being used properly. The actors don't have too much to do beyond react appropriately: Gamble, playing Drayton's young son, has basically three expressions the entire movie: scared, terrified and traumatized into catatonia [the third can be seen in the photo, right]. However, the reactions are largely sensible, even those of Mrs. Carmody, and that allows the film to work on another level, a Lord of the Flies-style disintegration of society. If much more in your face than Darabont's previous King adaptations (The Green Mile and The Shawshank Redemption), it's absolutely no less effective, and does exactly what it should: deliver terror.