From the title of this book I assumed for some reason that the main character would learn magic at the hand of a good witch to whom he was apprenticed. I wasn't too far off in my guess as he does end up learning magic but not quite in the way that I imagined. Ned, the aforementioned witch's boy was one half of a twin until one day he and his brother take to sea in a flimsy craft and end up stranded. Ned himself only survived due to his mother's heroic use of magic. Circumstances soon conspire to bring big trouble to his neck of the woods though as the bandit king and his army raid their village and try to steal the magic which Ned's mother has safeguarded.
Set in a time far off when kings and queens ruled we see the level of ignorance and distrust that exists among people in the same town and between peoples of different towns. Ned's people for example don't think that there is anything beyond the mountain. Aine's people think that Ned's people are simpletons. Even Ned's people are afraid of his mother despite the fact that she is called upon to help them when any misfortune occurs.
Another good theme that I found in this work is that of the strong woman. I read something recently about staying away from the damsel in distress trope and Barnhill does a good job of this. There are three main characters in this book and non can be classified as "weak": The Queen, Sister Witch (Ned's mom) and Aine, daughter of a red-haired bandit king whose name we never learn. The Queen, despite her advanced age is in control of her faculties and is a kind and just ruler. Ned's mom exercises her office and uses her power wisely-many times she uses herbal remedies instead of magic-and is a good bridge between Ned and his father. Aine for her part has been taught well by her father and can defend herself if need be. It is she who takes pity on Ned when they first meet because he has no experience living in the wild and is dependent on her for instruction.
Power corrupts is another theme and we see it in the machinations of the Queen's family who try to usurp the throne many times. The boy King is another character who abuses his power and Aine's own father cannot curb his baser instincts and returns to the life that he lived before he met Aine's mother. Aine for her part tries to make sense of the abrupt change her father seems to have undergone. She out of all the characters struggles with some very heavy issues. She is a brave girl indeed. Life must go on and loss is a part of life and I thought that Barnhill did an excellent job with dealing with the loss of loved ones in this book. Older readers aged 10+ would grasp what she is trying to convey.