Spellbound — Anna Dale

An innocent summer holiday turns out to be anything but for Athene and her younger brother, Zach, when they find themselves caught up in a skirmish between two groups of gnome-like creatures: The Humble Gloam live above ground and get along with humans; the Low Gloam live below ground and despise everyone. But when Zach stumbles into Low Gloam territory, Athene disguises herself to rescue him--and discovers a secret that could bring the two Gloam tribes together--if it doesn't tear them apart first.