What can I say? I loved this book so, so much. Hitomi is a Promise, a magic user who hasn't been formally trained - although her parents have taught her the basics, in secret. At the beginning of Sunbolt she's working with a secret organisation, trying to undermine the evil mage who controls their land, but when a job goes wrong she ends up imprisoned. Her resulting journey pushes her to use her raw magical talent to save herself and others, a process that utterly exhausts her. The story is pacy and action-packed, but despite some thoroughly despicable characters along the way, manages to maintain a broadly optimistic tone. 
 Full review to follow.