The Tears of the Sun : A Novel of the Change (Emberverse‪)‬

It's Change Year 25, a generation after high-energy technology died in a catastrophe most of the human race didn't survive.

The children born after the Change are now starting to take center stage—and Whoever or Whatever was behind the Change itself may be taking a hand in their rivalries. An expedition has travelled to Nantucked across a strange and hostile continent to find some answers.