by Vernor Vinge
In 1968, a short story entitled "Grimm's Story" appeared in an anthology. A year later, an expanded version of this story was publshed as Grimm's World. Vinge came back to the story in 1986 with a sort of prequel published in Analog entitled "The Barbarian Princess". For whatever reason, Vinge decided to put it all together, and in July of 1987, Tatja Grimm's World was published.
The story centers around a superhuman heroine, a feral human or alien child who, for lack of anyone smart enough to hang out with, decides to take over the world. Tatja soon finds another of her kind, and must fight to save the stupid regular humans she so detests from a sinister foe, for some reason.
While the story and characters may not be particularly compelling, what makes this book worth a read are the details. Everything takes place on a planet that is nearly devoid of metals, with humans at a period of technological development roughly analogous to the tail end of the Middle Ages. Now tell me, how would you invent a cannon without iron? Vinge also includes a barge housing a 1,000 year old mobile publishing company (dedicated to contrivance fiction), a small mammal capable of mind control, and interesting uses of glass as a structural material.
This book is out of print, but you can probably find a copy at your local used bookstore.