In eastern Pennsylvania, Marcus believes in doomsday and has long prepared for it. He has instilled this belief in his adult children Geoff and Melissa, although Melissa has quietly rebelled in some of the "soldier" training, preferring rather to do things like sing in the church choir. Marcus also has a small following. This preparedness does not help Marcus as when a large radioactive meteor hits the area, he is caught outside the sealed bunker, while Geoff, Melissa and most of his followers make it to safety inside. Fast forward ten years. Most of those inside the bunker are still alive and have not left it not knowing definitively what has happened outside. But some are forced to go outside when something happens to one of the bunker's exterior solar panels, which must be repaired within three days for their survival. A small team, including Geoff and Melissa, volunteer not only to go outside to repair the panel, but to survey their exterior surroundings. Outside, they find that the world has turned into a desert wasteland seemingly devoid of any life. They soon discover however that the radioactivity, which has dissipated, has not killed everyone but has turned some of those exposed to it into killer mutants. They will also discover the hard way that the there are different levels of mutancy depending on the level of radioactive exposure. In dealing with the mutants in which they get a little unexpected help from a preacher, they also learn that there is a place in this outside world called Haven which truly is a sanctuary where they can survive outside the bunker. They have to try to make their way to Haven while dealing with the killer mutants, which may include some friends and other loved ones from their pre-meteor life.