Slaves of the Mastery (Wind on Fire, Bk. II) - William Nicholson

I didn't think there was much to do in the sequel, having basically overturned the entire city in the first one, but turns out a few years later there's more massive upheavals to come. Characters are just as great as the first one, have aged well, no continuity errors. This book is great. :)

 

-Lyrael