Ella's mother is ill with cancer, so she is sent to the home of her quirky grandmother (known as GM), where she at least has the company of Rosie, the daughter of a man who works for GM. After a disturbance on the grounds one night (and there's a map at the beginning of the book), GM discovers that a valuable book has been stolen from their library; Kepler's Dream. Ella's grandfather, who was an astronomer and knew Michael Collins, valued the book, so Ella (who has nothing better to do with her time) decides that she will discover who the thief is. Her investigation involves research into a variety of books, and keeps her mind off her mother's sickness as well as the relative dysfunction of her relatives.
Strengths: Have a feeling that this will get a lot of buzz and may even win an award. It has all of the elements that adults tend to like in middle grade books; quirky characters, a bit of history, clue-oriented mystery, and family angst.
Weaknesses: I find that these elements make for a hard sell in my library, especially when the plot is rather slow paced.