The Inside Story, by Michael Buckley
I have been wrestling with this review for a while now.
Buckley says that this was the most difficult book in the series to write, and I am not at all surprised. The overarching theme of the book, after all, is fictional characters that don't want to do what they are supposed to do.
Daphne, Sabrina, and Puck chase Mirror, Pinocchio, and Baby Boy Grimm into a book that recounts the origins of the Everafters. At some point in history, someone changed the nature of the book so that events in the book will affect events in the real world.
In order to combat this, a previous Grimm invented someone called the Editor. The Editor's job is to restore the storyline to its original form using little creatures called the Revisers, which add a whole new meaning to the term "pink eraser."
Daphne and Sabrina have to chase Mirror through the stories of the book. Every time the story ends, a door appears which will take them to the next story.
There are two forms that the theme of characters who don't want to do what they are supposed to take.
First, a number of characters are tired of living the same lives over and over, and they want to escape the book. Even once they have been informed that they would never be able to leave Ferryport Landing, they still would prefer that prison to this one.
Second, is Daphne and Sabrina themselves. Since they are real people the Book stuffs them into the roles of characters within the story. But Sabrina and Daphne don't have time to go through ever step of the books they end up in and so they are continually trying to cut corners to make the ending come more quickly.
We eventually find out what story was changed that led to the Book being linked to reality and we have some inkling of how it was changed. We are told, for example, that it was originally a tragic story, but it now has a happy ending. However, even at the end of The Inside Story, we still do not know how the story originally ended, or who changed it.
The Inside Story ends on quite a cliffhanger. I haven't read the final book, The Council of Mirrors yet, but I expect it to be a doozy.