Saving Sky by Diane Stanley

The country is at war, terrorists strike at random, widespread rationing is in effect, and the power grid is down. But thirteen-year-old Sky Brightman is remarkably untouched by it all. She lives off the grid on sixty acres of rural New Mexico ranch land with chores to do and horses to ride and no television or internet to bring disturbing news into her family's adobe house. Sky's schoolmates think she's a little weird.

Then a string of mysterious arrests begins, and her new friend, Kareem, becomes a target. Sky is finally forced to confront the world in all its complexity. Summoning her considerable courage and ingenuity, she takes a stand against injustice. With humor, hope, and fierce determination, she proves that even a child can change the world.