Watch out for spoilers about the first book.
At the end of Book One, Rossamünd Bookchild had completed his arduous journey, turned down Miss Europe's job offer and arrived at Winstermill to begin his training as an apprentice lamplighter. One would think that his adventures would have stopped there -- or at least slowed down.
Being a lamplighter -- even an prentice-lighter -- is a dangerous job. On almost his very first excursion out, Rossamünd witnesses (and participates in) a battle with some monsters who have attacked a coach-and-six on the road. One of the passengers on the coach is Threnody, the daughter of the Lady Vey, who, in an attempt to defy her mother, has decided to enlist as a prentice lamplighter.
About halfway through the book, I had a Thought. That Thought quickly developed into a Theory. And by the end, ah-hah! I was positive* that I was right! But that's ridiculously spoiler-y, so I won't continue talking about it.
D. M. Cornish has done a fantastic job of creating another world. It's a world where most people see things in black and white -- Monsters-Bad, People-Good -- and where seeing shades of grey can lead to execution. That's just a tiny aspect of the world -- it's convincing and rich and well thought out in every other way I can think of. The people in it have their own language, complete with dialect and slang, their own beliefs and taboo subjects, their own politics and factions -- and so, I suspect, do the monsters.
Each chapter begins with a dictionary entry that explains a term about to be used, and the last hundred pages in the book is a glossary. There are maps at the beginning and the sketches, as in the first volume, are fantastic and the style is a perfect match for the story. It's certainly not a book that I'd put on the Quick Picks list or hand to a reluctant reader, but wow, in the right hands? You'll have some readers doing back flips.
Definitely, definitely, definitely read these books in order. Cornish gave me enough information to jog my memory about what came before, but only just barely. It'll be possible to read this one on its own, but there's SO MUCH going on that I would not recommend it. YAs who like complex fantasy, who don't mind doing a little work when they read, will appreciate it. Adults who appreciated the language and flavor of Jonathan Strange and Mr. Norrell also may enjoy this series. I'm planning on testing that theory on Josh.
*Okay, mostly positive. Do I seriously have to wait a whole year to find out for sure? GAH.