The small town of Sullivan has barricaded itself against the outside world. It is one of the last enclaves of civilization and the residents are determined that their town remain free from the strange and terrifying plague that is sweeping the land--a plague that transforms ordinary people into murderous, bloodthirsty madmen. But the transformation is only the beginning. With the shocking realization that mankind is evolving into something different, something horrifying, the struggle for survival becomes a battle to save humanity.