This is a very short book/novella that, evidently, sets up Card's next series. In some areas, the book is a little slow, as the characters are explaining some of the information we would need about this particular universe.
Here, there are mages which control different elements (water, stone, animals, etc.) and they're known as mithermages. This book deals with some political issues surrounding a city that once belonged to Stone mages but was taken over by water mages. Into their midst comes a boy who is (unknowingly) a stone-mage. This story feels more about the universe he inhabits than what really goes on, but if it is a set up, it's a pretty decent one.
I don't know if I'll continue in the series, but for someone reading the series, this book is probably pretty good.