In McKinley's version of the classic fairy tale, Sleeping Beauty, a wicked fairy named Pernicia appears on the princess' name-day and places a curse on the baby, claiming that the child will, on her 21st birthday, prick her finger on a spindle and fall into deathly sleep.

The cursed princess is rescued on her name-day and secretly taken away by a young fairy, Katriona, to her village, a town called Foggy Bottom, located in the damp and swampy section of the country known as The Gig.

With the help of a rare talent—beast-speech, a small bit of magic unknowingly passed on from Katriona—and the silent encouragement of the town's taciturn blacksmith, Narl, Rosie becomes a talented and well-known horse leech, more inclined to wear breeches and whittle spindle ends than wear dresses and practice embroidery, as her more ladylike friend Peony does.

In addition to the magic that infuses almost every aspect of the book, Spindle's End deals with the importance of family love, especially that between Rosie, Katriona, and Aunt, (and, later, the love between these people and Katriona's husband and children, as the family grows) but also of Rosie's mother, the Queen, who longs for her lost daughter.

F&SF reviewer Charles de Lint praised Spindle's End as "luminescent," characterizing the novel as "one of those rare occasions when the writing is so good, and the novel has so much heart, that the plot almost doesn't matter.