This book is about confusion: the confusion of the Londoners as a comet approached the city closer and closer in the middle of the 18th century; the confusion of Sabian Blake, who knew more about the sky-dragon, thanks to a dangerous book of secret knowledge sent to him by a mysterious person. And the readers are supposed to be confused too: characters appearing suddenly from alleyways, doing their own things, seemingly unconnected with the other events in the book, and then fleeting away as if they don't have anything to do anymore with the plot, and then appearing again under disguises, to the point that I wonder just who is the main character actually.
Yes, it's a maze, or perhaps - since a maze is supposed to make people get lost while a labyrinth is not - a labyrinth that will finally lead us to an exit, where finally we have enough light to make sense of everything.
At the beginning, the book was pretty blatant though, describing the protagonist Blake as a scientist and a Cabalist right on the first page, instead of letting us find it out gradually. This rather spoils the fun of getting the truth about our hero (for lack of a better word); it's as if he is just thrown to our face and we just have to digest the fact that he is everything as he is described.
After a few chapters, the book begins to take pace, and that's when everything gets really exciting, with creatures lying in the dark ready to leap at you, and the world sliding into disgrace, to be conquered by a harlot.
Enticingly, menacingly dark, and violent but not vulgar, the book is a fascinating blend of history, science, religion, and magic, although I wish Blake's status as a scientist/Cabalist could have helped him more. In this book, he was just more like a pawn, a lost sheep struggling with his science only to know that there were things more beyond his grasp; and how it hurt his pride so much to find out that what he had thought as things he'd done by his profane human might were actually some kind of divine help. Instead of just swinging his swords now and then, it would be more in-line with his character if he used some scientific or esoteric knowledge he had to at least save himself. Something like, say, Horatio Lyle would do.
What some readers may be concerned about Wormwood is the lack of morality shown by the characters, although this poses no problem for me. They gave out to temptation, greed and anger; nobody, even Blake with his conscience to try and save Londoners, is squeaky, glitteringly clean or innocent. Abram Rickards surely lacked morality, laughing while stuffing exploding crystals into the 'stink hole' of a beastly creature - but, for what he was, that's just what was expected of him. And that is what makes him memorable.
A precious addition to the bookshelves of people who love fantasy.