A Circle of Flames — Kate Avery Ellison

Briand has been taken captive by her mortal enemy, Auberon. As he takes her to the capital city of Tasglorn, she schemes to barter for her release by attempting to cooperate... and learn what she can about her magic gift. Meanwhile, Kael gathers old friends in a desperate bid to rescue her from the Seekers' clutches. Briand thought the Seekers were monsters. She's surprised to find they are more human than she could have imagined. Sometimes she even forgets they are her enemies. With her loyalties tested and time running out before her magic kills her, Briand must prove herself Catfoot yet again.