The Girl Who Circumnavigated Fairyland in a Ship of Her Own Making — Catherynne M. Valente

Twelve-year-old September lives in Omaha, and used to have an ordinary life, until her father went to war and her mother went to work. One day, September is met at her kitchen window by a Green Wind (taking the form of a gentleman in a green jacket), who invites her on an adventure, implying that her help is needed in Fairyland. The new Marquess is unpredictable and fickle, and also not much older than September. Only September can retrieve a talisman the Marquess wants from the enchanted woods, and if she doesn't . . . then the Marquess will make life impossible for the inhabitants of Fairyland. September is already making new friends, including a book-loving Wyvern and a mysterious boy named Saturday.