Shield of the Sky — Susan Krinard

Ever since witnessing a sacred ritual, Rhenna of the Free People has been isolated. Not outcast, yet not part of her tribe, she walks alone, guarding the land's borders. And growing more troubled by the changes in the wind. Anger and war are rising. The mountain-dwelling shapeshifters -- partners to the Free People -- are disappearing, and word has come of an evil new god:The Stone God, whose followers are known by the red stones they hold and the chaos that accompanies them.

So when Rhenna hears that a shapeshifter has been captured by the Stone God's servants, she must rescue him. Now Rhenna is embroiled in a dangerous game as the forces of evil and nature fight to control humanity's future.Together with a growing band -- the enigmatic shaman Tahvo, the panther shapechanger Cian and the rebel Quintus of conquered Tiberia -- she must travel the world, seeking to prevent its destruction.

Whatever danger lies ahead, the downfall of the Stone God has begun....