Darkness on the Edge of Town — Brian Keene

One morning the residents of Walden, Virginia, woke up to find that the rest of the world was gone. Just...gone. Surrounding their town was a wall of inky darkness, casting Walden into permanent night. Nothing can get in, no light, no people, not even electricity or radio or TV signals. And no one can get out. No one who dared to penetrate the mysterious barrier has ever been seen again. Only their screams were heard. But for some of the residents-turned-prisoners of Walden, even the fear of that unseen death can't keep them from trying to escape this living purgatory.