This is the story of the Norman Conquest, with the twist of real magic. I don't know the history very well, but I did know where the story had to end up. Perhaps because of my ignorance of the subtleties of history, and perhaps because of Tarr's license, I actually got a more surprising plot than I expected. The magical elements are well imagined and well told, and the characters are interesting and sympathetic. Tarr's prose flows well. Yet I had trouble getting into the story -- I think mainly because it's broken into a lot of short chapters. I've been distracted by enough other things that I haven't actually been reading except at bedtime, and the short chapters mean I'd only read a chapter or two most days; with over 50 chapters, it took a lot of days. That kept me from getting into the flow of the book as well as I should have -- but it does say that the book wasn't so engaging that it pushed itself into my attention more forcefully.
I have a spoilery question about the history. The big surprise for me in the plot was that Harold becomes William's friend and swears to stand behind him as Edward's heir. In the book, William is the legitimate king and Harold the usurper. On the off chance that anyone knows the history and has read the book, I ask: how much of that is historical, and how much is invented? It doesn't make a bad plot, but it was surprising to me. Is that because I don't know history, or because Tarr made that bit up? If Tarr did make it up, does the story still work if you know the history well?
So, a solid book, but maybe not quite as good as many of Tarr's. (Or maybe it's just me.) 8 out of 10.