The second book in this series didn't act as filler or a place to add new characters, like many second in a series or middle book in a trilogy. The evil man identified in the first book is challenged and found wanting. Was he a mere figurehead or had he been unknowingly conquered by a larger cabal? Jane gets an unexpected assistant in the fight, one who pays a high price by joining the battle. We do get a chilling insight into the mindset of the people spreading this plague. It makes one value our independence just a little bit more.
The story moves very fast. I enjoyed the adventure aspects of the book, but the parts that make you stop and think are even more enjoyable. I really like books that slide philosophical ideas in without beating you over the head with them.