The Sunrise Lands by S.M. Stirling

Part Of The Synopsis From The Dust Jacket:

Rudi Mackenzie-the son of the High Priestess of Clan Mackenzie and the Bear Lord of the Bearkillers, the two groups responsible for establishing peace in western Oregon-will one day assume leadership over his people.  But a prophecy made at his birth spoke of an even greater destiny for the young man-a destiny that is about to be fulfilled.

It's been 22 year since The Change that set civilization back hundreds of years and life has fallen into a steady rhythm the Willamette Valley in what was once Oregon  That is about to change when a stranger from the East arrives and tells them of what's been going on in the rest of the former United States. 

There are strange events taking place on Nantucket Island, long though to be the source of everything that's happened.  Added to the mix is a brewing war between The United States of Boise and the Church Universal and Triumphant.  The Church, which claims most of what used to be Montana, has as one of it's founder the Uni bomber, so needless to say it's not exactly one of the good churches.  They have been warring for a while with New Dessert, think the remnants of the Mormon Church in Utah, and have almost wiped them out.  They are now turning their sights West and will quickly be making there way to the Willamette.

All of this is set as a backdrop for the quest that Rudi and his friends must undertake to find out what it is The Lady wants of him on Nantucket.  It's a perilous journey that gets underway in this book, one that is fraught with danger and betrayal.  Rudi and his friends find themselves in unfamiliar territory and are forced to relay on their wits and new allies they meet on the way. 

This is a promising start to the next chapter in the series and one that I'm looking forward continuing.