First Truth Truth Series, Book 1.

Alissa doesn't believe in magic. Her father's stories about the Hold, a legendary fortress where human Keepers learn magic from the enigmatic Masters, are just that-stories. But her mother insists Alissa has inherited her father's magical ability, so she must go to the Hold to be trained. On her way, she crosses paths with Strell, a wandering musician from the plains. Though Alissa is not sure she can trust a plainsman, Strell has something Aliss...