A hundred years from now, an impenetrable fence divides the old United States across its middle from coast to coast. Uncontrolled extremes of conservatism and liberalism have split the once great country in a violent civil war that ended only by separating the two ideologies into separate countries, the Democracy of America in the north and the Republic of America in the south. But bitter hatreds and age-old grudges are nothing compared to a mutated parasite that threatens all of humanity by turning them into cannibals. Now the two countries are forced to cooperate in a race to find a cure before they are all destroyed.