3.5-4 starsIt's tough to rate this book... it's tough to categorize this book. That's not a bad thing, and this is not a bad book - quite the contrary, actually. But as much as it's familiar, this book is all-new and strange again - another strange, new world. For as much as we learn, there are a host of other secrets and lies... most of which are not revealed. There are familiar names (like Lightwood and Herrondale), vampires, warlocks, Silent Brothers, and Shadowhunters. There is an Institute. But this book and it's companions (The Infernal Devices) are only connected to The Mortal Instruments; they are not the same - this is not the same world. This might be book 1 in that series and book 4 in the overall set of books, but it's definitely its own story arc.The Accords have only been in place for about 10 years or so. It's Victorian England - London 1878. We have a whole new set of characters, mostly the trio of Will (William) Herrondale, Jem (James) Carstairs, and Tessa Gray. Will and Jem are 17 or so and Shadowhunters. We don't know what Tessa is; no one seems to know. Tessa is American and about the same age as Will and Jem; she has the ability to Change - by holding an object that belongs to someone else, Tessa can physically change into that person. She can even discern his or her thoughts. While it's easy to assume that she's a warlock, she doesn't bear the mark of one; and her ability is one of legends and myth. And that's part of my beef with this book. We never do find out what Tessa is or how she fits. OK, OK, this is, technically, another 3-story arc in these Victorian/Steampunk times. The Infernal Devices are automatons that can be animated using demon energies (much like the vampire motorcycles from The Mortal Instruments).There is a London Institute, run by Charlotte and Henry Branwell... well, by Charlotte. Henry is a tinkerer and inventor; the stereotypical absent-minded professor type. Charlotte is only 23, but she's responsible for the Institute and for Will, Jem, and Jessamine, the underage Shadowhunters in her care.There is a villain - no, not Valentine, but someone referred to only as The Magister. And he wants Tessa. So much so, that he has her brother, Nathaniel (Nate); after Tessa's aunt died, Nate sent Tessa a ticket to London. But when she arrived, The Dark Sisters took charge of her and forced her into learning about her ability to Change. Tessa had no idea that she was capable of it. And just as the Dark Sisters were going to hand Tessa over to The Magister, the head of the Pandemonium Club (yes, that's a familiar name), as his bride, Will broke into the Institute, slew one of the sisters, and grabbed Tessa.What ensues is quite the story... filled with secrets and lies. Lots of them. And not many revelations - enough for this book's beginning, but not nearly enough to understand the new characters and what's really going on. While Tessa desperately searches for her missing brother, the Shadowhunters try to discern what's up with the automatons that they found at the Pandemonium Club, the Dark Sisters' lair. There's magic and demon energies involved in these devices... and human parts, like skin and magicked hearts. Humans have been slain to create them. Why? What is their purpose?Through Tessa's reading of the Shadowhunter Codex, we learn a lot more about the origins of the Shadowhunters and various weapons. The kind of information that I wished I'd had in the previous 3 books!But it would be a disservice to compare the characters. Jace is not Will. Tessa is not Clary. And so on.My beef with this book is that I don't know enough about anyone or anything in it to feel as if I can rate it accurately just yet. As much as I know, I feel as if I know nothing at all. I can't even judge if I think the writing is better or worse. I got into the story, but... And because of the suggested reading order, I won't be back in these stories until I get thru book 4 of The Mortal Instruments series.So, for now, I'm going to rate this book at 3.5 stars. And probably come back to it after reading book 2. Perhaps by then, my frustrations will be assuaged or diminished.