"Cussy Mary Carter is the last of her kind, her skin the color of a blue damselfly in these dusty hills. But that doesn't mean she's got nothing to offer. As a member of the Pack Horse Library Project, Cussy delivers books to the hill folk of Troublesome, hoping to spread learning in these desperate times. But not everyone is so keen on Cussy's family or the Library Project, and the hardscrabble Kentuckians are quick to blame a Blue for any trouble...

A family living in the Appalachian Mountains in the 1930's gets books to read during the regular visits of the "Book Woman" - a librarian who rides a pack horse through the mountains, lending books to the isolated residents.

Enrolled in school after her mother's death, Possum resolves to preserve her mother's homeschooling lessons by proving she already knows everything, an unsuccessful endeavor complicated by her teacher's attraction to Possum's father.