A Feather of Stone by Cate Tiernan (Balefire #3)

Thais has finally begun to unlock the magick within her, while Clio begins to experiment with higher magick than she has ever used before. Someone is still trying to kill the sisters and they still have much to learn about who the Trieze really is. This third book in the Balefire series picks up right where A Circle of Ashes left off. The twins continue to develop as characters, as do the secondary characters in the series. New surprising plot twists bring interesting changes to the story. Like the previous books, this book only brings up more questions. Readers will be anxiously awaiting the fourth installment (scheduled to be published in March 2006).