Almost all of humanity has been destroyed on the North American continent by a series of catastrophes, including famine, plague, and floods.
 
Descendants of the survivors (those who stayed) created a tribal society in the American West which lives side by side with an enclave of scientists.
 
Earth has kept its rebirth a secret for some time, but when colonists throughout the stars begin to long for contact with the mother world, violence and greed could once again threaten the planet.