The Wishsong of Shannara (Paperback) by Terry Brooks

An ancient evil is stirring, intent on the complete destruction of all life. The Druid Allanon sets out on a dangerous journey to save the world, reluctantly aided by Brin Ohmsford, daughter of Wil Ohmsford—for she alone holds the magic power of the wishsong. But a prophecy foretells doom, as evil nurses its plan to trap the unsuspecting Brin into a fate far more horrible than death.