Shadowfell

In the final book of the Shadowfell trilogy, Neryn, the rebels, and the Good Folk must work together to survive their final confrontation with King Keldec.

"Neryn has finally found the rebel group at Shadowfell, and now her task is to seek out the elusive Guardians, vital to her training as a Caller. These four powerful beings have been increasingly at odds with humankind, and Neryn must prove her worth to them. She desperately needs their help to use her gift without compromising herself or the cause of overthrowing the evil King Keldec. Neryn journeys with the tough and steadfast Tali, who sees Neryn's love for the double agent Flint as a needless vulnerability. And perhaps it is. What Flint learns from the king will change the battlefield entirely -- but in whose favor, no one knows."--from back cover.

To rescue her homeland from tyranny, Neryn must seek out the powerful Guardians to complete her training as a Caller.

Fifteen-year-old Neryn is alone in the land of Alban, where the oppressive king has ordered anyone with magical strengths captured, but when she sets out for Shadowfell, a training ground for a rebel group, she meets a mysterious soldier and the Good Folk, who tell her that she, alone, can save Alban.