This is an exceptionally well-written fantasy that offers something different from the usual themes and characters. Sperring's heroine, Aude, comes from the upper class of a society based on a sharp division between the rich and the poor. When her awakening social conscience drives her to discover the source of her family's wealth, she finds herself trapped in a strange and magic land, the WorldBelow. While her husband desperately searches for her, Aude must find the answers she seeks or stay trapped forever.
One thing I particularly liked about the book is its non-human characters. (None of them are the usual elves and dwarves.) They are as alien as any you'll find in well written SF, and some, like the ferret women, are both comic and threatening. This is not easy to pull off.
One thing the book is not is a "fast, fun read" as too many books are these days, mind candy that's instantly forgetable. Sperring gives the reader things to think about and clues that the reader must put together as the heroine finds them. And because of this, the book is absorbing and memorable.