Willa of the Wood - Robert Beatty

The first in a new series from the #1 "New York Times"-bestselling creator of the Serafina series. Willa, a young night-spirit of the Great Smoky Mountains, is her Faeran clan's best thief. When Willa's curiosity leaves her stranded in the day world, she soon discovers that not all day-folk are the same, and the foundations that have guarded the Faeran for eons are under attack.