I purchased this book from my local second Emmaus yesterday and couldn't put it down. I have read an other book by Robin McKinley, Spindle's End. and enjoyed it just as much.
The Blue sword is about a mythical place, although you are not quite certain whether or not it does exist, as it has overtones of the raj running through it, making the area Daria feel like India.
The heroine Angharad (or Harry as she is known), travels out to Daria to be with her brother Richard after the death of her father, in the Homeland. There she is taken into the house of Richards boss, Sir Charles and his wife. Lady Amelia. Here she can see the range of mountains and she has a longing to explore.
When the local cheiftan (King Corlath) comes visiting, he finds something strange about her and kidnaps her.
She has the 'kelar' or magic which only shows itself to some of the hillfolk, and this leads her to become Harimad-sol and the laprun-minta. She, like shamen, can see into the future, and she knows that she will have to go against the wishes of Corlath to save both his people, their homeland in the mountains as well as the land where the Homelanders live.
A thrilling book, one which kept up its pace from start to finish, and I was sorry when it ended as I wanted to read on.
If you have not read any books by Robim McKinley before, this is an agreeable read, light but engrosing.