From a reader on Amazon.com:
I picked this book up in a used bookstore I used to frequent (the only reason I don't is because I don't live in that town anymore) I was already familiar with Ms. Green's work, and decided to read it. I'm glad I did. Set in the same universe as her Hidden Realms/Silver Princess series (the main character is even mentioned in one of the books) it follows the powerful sorceress as she tries to save her wizard foster mother, with the help of some very powerful friends. This is the second book in a trilogy, unfortunately, the series is unfinished. The third book has never been published, an maybe never will. Though Ms. Green has told me that she is willing to write it, since the previous books have been allowed to go out of print, it seems unlikely.