This is the third book in the Dragonback series which started with Dragon and Thief (which I thought was good) and continued with Dragon and Soldier (which was not so good). This volume makes very little attempt to fill in the background, so you need to have read Thief at least to not be completely confused.
This is a much better book than the previous one in the series. It still suffers from the problem that the main cool thing about the series is the main characters and the abilities and oddities that they are created with at the beginning of the series, which we learned about in the first book. Which means they're not new in the third book. There is, however, plenty of breathless action, less overt preaching, and only one place where I noticed painfully bowdlerized language (a "no kidding, Sherlock"). It's still a YA adventure story, but it's not quite as condescending to the YA audience.
The big problem with the book, and in fact with the previous book and the main series plot arc so far, is that, while it's nice for Jack and Draycos to have such adventures, Draycos' mission is too vital to be entrusted to such wacko schemes as the ones they use to get themselves into the situations where the adventures happen. Yes, Draycos distrusts authority, but even if he survives the schemes, he's going to need a lot more help to actually solve his problem. In this book, the characters confront this problem head on and actually discuss how they can't possibly do this alone, but they still went ahead and did the stuff in this volume and the previous one, risking not only their own lives but also Draycos' mission. It solidly forces the story into the "don't think about it too much" category, but within that category, this volume is at least an entertaining romp.
It's fluff, but it's fun fluff, and it does leave me wondering where the series plot is going next. I'll trust that the second book was an aberration and plan on continuing to read the series for now. 8 out of 10.