The novel is about a girl from a normal-ish world who is thrust into a magical one in which she must learn to function and thrive. Corlath, king of the Hillfolk and guided by some kind of hereditary magic, kidnaps the girl, Harry, and takes her into the hills, which are threatened by the Northerners, who aren't quite human. Turns out Harry is good at riding horses and fighting, and she has some of the magic, too. They eventually fight the Northerners. Things are more complicated than that, of course.
I read The Blue Sword because it's one of Palmer's favorite kid-books, and, though he doesn't seem to be too fond of them anymore (Harry Potter is a kids' novel!), I see how he liked this one. It's really engrossing. It's one of those I'll confuse with a movie. There was some confusion as to which Robin McKinley novel was actually his favorite. There's a prequel to this one called The Hero and the Crown, but it was written after this one. It was supposedly going to be a whole series, but I guess that didn't pan out. She talks a bit about it on her webpage:
The bottom line is, it isn't my choice. You don't write stories like you might build a bookcase. You don't get up in the morning, decide that you're going to put seven chapters together to make a novel, whip out your tape measure and decide how many words, order the paper by the square foot from the office supply shop, sit down and start stamping the pages with black ink in a quantifiable pattern, and polish off the rough edges with a sander at the end. It's not up to you. You write what you are given to write, and you just go on hoping you will go on receiving those gifts. Damar hasn't seen fit to oblige me to write about it lately.
All of this, of course, seems like corny crap to me. It's funny how a photo of an author will immediately bias me for or against him or her. Robin McKinley reminds me of one of my high school teachers. It's actually kind of creepy. She also loooooves horses. The author blurb on the back flap of the first edition of The Blue Sword says that "Robin McKinley lives at present on a horse farm in eastern Massachusetts where she divides her time between the fascinating occupants of the barn in the mornings and the tyranny of her typewriter in the afternoons." She totally wrote that herself. What matters, though, is that I enjoyed her novel, and I'll be reading the next one in the near future. I like to put a couple unrelated books between ones in a series.