The book summary (from Indiebound):
Twelve-year-old Mosca Mye hasn't got much. Her cruel uncle keeps her locked up in his mill, and her only friend is her pet goose, Saracen, who'll bite anything that crosses his path. But she does have one small, rare thing: the ability to read. She doesn't know it yet, but in a world where books are dangerous things, this gift will change her life.
Enter Eponymous Clent, a smooth-talking con man who seems to love words nearly as much as Mosca herself. Soon Mosca and Clent are living a life of deceit and danger -- discovering secret societies, following shady characters onto floating coffeehouses, and entangling themselves with crazed dukes and double-crossing racketeers. It would be exactly the kind of tale Mosca has always longed to take part in, until she learns that her one true love -- words -- may be the death of her.
"Fly by Night" is astonishingly original, a grand feat of the imagination from a masterful new storyteller.