It was pretty obvious from Treasures that there had to be a previous book. There were too many references to important events. I couldn't believe that the story started where Treasures did.

I read The Rains of Eridan shortly after those two books, and I really bonded with that one. It's interesting in that the point of view character for the whole book is an adult. Looking at it now... There's a definite, mostly off screen oligarchy. There's a disease that makes people get really paranoid and mutiny and murder each other, and later, when outside forces come in, there are executions in spite of those people not being fully responsible.