November's recommendation: the Secret Country trilogy, by Pamela Dean. Titles are The Secret Country, The Hidden Land, and The Whim of the Dragon.

We should all thank the editor Sharyn November for bringing these books back into print. I mentioned them once before, when I recommended Dean's novelization of Tam Lin, but at the time they were very hard to find. I think I paid nearly forty bucks for my copy of The Whim of the Dragon, having decided I would buy it if I ever saw a copy available for less than fifty -- and I had to wait quite a while to catch that relative bargain.
This series invites a comparison to Narnia. A group of five children (two sets of siblings, cousins to each other) have for many years been playing a game of make-believe with each other, and then suddenly they find themselves in the world of their own story. Not the most original premise, but I love what Dean does with it. The children's game is somewhat like live-action role-playing, in that they dress up as their characters, but it's not improvisational; they have a fixed (and rather complicated) story, which they keep refining every summer when they visit each other. It's full of intrigues and has a large cast of characters, which they take turns playing. There's a character analogue for each of the children (named the same, but somewhat different in personality), but most scenes require them to play other individuals: the King of the Hidden Land; the wizard Fence; Randolph, the loyal adviser who betrays and poisons the King because it's the only way to save the Hidden Land from danger.
But one family moves to Australia, and for the first time, the cousins cannot spend the summer together, and cannot play their Secret Country game. Right on cue (in that children's-story kind of way), each set of children finds a magical sword which leads them through into the Secret Country . . .
. . . which is not exactly the way it's supposed to be.
Narnia comparisons go out the window rather fast at this point.
Certain details are just wrong. Some of them are small: the castle is built of granite that really can't be called any color other than pink, no matter how much the cousins want to say it's red. Some of them are not so small: there's a woman named Claudia at the castle, who wasn't in any of their stories. People don't behave like they're supposed to. Fence is far younger than they had said. The cousins try to change things the way they would if this were their game, and they fail -- mostly.
This is all a problem because the cousins have been mistaken for the royal children, their character-analogues, and cannot get back to the places where they could return to their own world. But they can't even tell whether they are the royal children -- whether this is a story come real, and they're supposed to play their parts in it -- or whether there are five people like them who are now missing. Either possibility has some unpleasant implications. Randolph is supposed to poison the King and then be killed by Prince Edward in the rose garden, but Ted finds to his dismay that he likes Randolph and doesn't want to kill him at all. Things that made splendid stories when one was playing a game become decidedly less splendid when the characters are living, breathing people with minds of their own.
The cousins have a lot of questions to answer (what's up with the swords that brought them into the Secret Country? what, if anything, happened to the royal children? can they keep Randolph from killing the King, and if so, should they?), but the question that underlies it all is how the world they seem to be in relates to the game they played. Did their story-telling create this place, and all the people in it? Certainly the people of the Secret Country quote fragments of Shakespeare and real-world folk music, as the cousins did when playing. Or was their story a reflection of the Secret Country, one which acquired inconsistencies in the translation? And what, if anything, does this strange woman Claudia have to do with that question?
According to her website, Pamela Dean is writing another Secret Country book, at long last. Apparently Going North will manage to be a sequel to both The Whim of the Dragon and The Dubious Hills, the latter of which (if I'm remembering my terms correctly) is set in the Secret Country (the world) but not the Hidden Land (the kingdom). I'm not sure how they're going to get linked up exactly, but given that both of those books have somewhat unsatisfactory endings, I can't wait for something that might carry them onward. Yes, this means I did just recommend a trilogy that doesn't end terribly well. It's because the books are fascinating anyway, and I love the characters. Especially Ruth, and especially Ruth when she's dealing with Randolph. She gives a great example of what it's like to be a teenager who's aware of the pitfalls of being a teenager, but still can't quite escape them.
And with any luck, Going North will be fantastic, and then I can do a recommendation for that one, too.