This fun, fast-paced sci-fi trilogy takes place on a terraformed asteroid mining colony, where children survive an attack, then race to solve the mystery behind the raiders. As the mystery escalates, the children face moral dilemmas related to warfare and socio-economics.
Certainly some young readers may not be ready for or enjoy this "kids at war" series (similar to, but smaller scale than, Ender's Game or Harry Potter). Yet as society's "War on Terror" shows no end, this story is excellent at illustrating how different perspectives, propaganda, economics, and politics make the term "terrorist" complicated. The story also shows how leaders struggle with trust, team consensus, and difficult choices.
My only nitpick was shaky science sometimes rattled my suspension of disbelief (few middle-grade readers will have problems with the science though). Overall, great sci-fi/fantasy is an allegory for the modern world and human behavior, and the first two books excel at this (the books would spark a lively discussion in any children's book club or classroom). I eagerly await the final installment!