Dark Witch (The Cousins O'Dwyer Trilogy)

With only the most basic understanding of her powers, Iona Sheehan leaves America for Ireland in search of family, destiny, and home. She finds all of it in the deep green woods near the shadows of the great castle of Ashford. There, as the third hereditary Dark Witch, she'll join forces with her two cousins--and the man she comes to love--to break a centuries-old curse, and defeat the ancient evil that seems to destroy them all.