The Sunrise Lands (Emberverse Series #4)

Young Rudi Mackenzie has grown up knowing that he will one day assume leadership over the Western Oregon survivors of the technological disaster called the Change. But a prophecy made at his birth spoke of an even greater destiny—a destiny that is about to be fulfilled.
           
A mysterious traveler has arrived in the Willamette Valley. He brings news from the East, from Nantucket Island, long rumored to be the source of the Change. He has been sent on a mission to bring back with…