In 1936, tucked deep into the woods of Troublesome Creek, Kentucky, blue-skinned nineteen-year-old Cussy Carter, the last living female of the rare Blue People ancestry, has just snuffed out her last courting candle, her last chance for 'respectability' and a marriage bed. The lonely young Appalachian woman joins the historical Pack Horse Library Project of Kentucky and becomes a librarian, riding across slippery creek beds and up treacherous mountains on her faithful mule to deliver books and other reading material to the impoverished hill people of Eastern Kentucky. Along her dangerous route, Cussy, known to the mountain folk as Bluet, confronts those suspicious of her damselfly-blue skin and the government's new book program. She befriends hardscrabble and complex fellow Kentuckians and is fiercely determined to bring comfort and joy, instill literacy, and give those who have nothing a bookly respite.