how on earth i managed to forget halfway through that this was only the first part of something is beyond me. but i did. 
 and i wouldn't call that ending a cliffhanger so much as a non-ending. and i don't mean that as criticism, although it sounds like one. were this not part of a series, yes, those would be fighting words, but since there is more to come, i will just say i was...surprised that it ended where it did, and it felt like almost 600 pages of buildup that left me a little stranded. 
 this has been billed as the matrix meets inkheart. i have not seen the matrix. i have not read inkheart. i know what both of them are about, more or less, but i can't tell you how much this book is informed by them. she refers to so many specific scenes from the matrix that i think it would have been helpful for me to have had that in my back pocket o'references. however, she does allude to several other movies i have seen: shutter island, inception, identity (WHY, john cusack, WHYYY?), so just by looking at those movies all grouped together, you have a pretty good sense of what this book is about and the way it is going to play with reality/illusion/artifice. 
 my caution to you: the first chapter/thirty pages is kind of a trial to get through. she thrusts you into an off-kilter situation with lots of white space-specific vocabulary: dark passages, nows, panops, peculiars, thought-magic glass, sign of sure, dickens mirror, monster-doll, hanger-on, and i was very "it is that kind of book?? i don't yike it!!" and it's a situation you will not understand until you get further in. the tone of it was very dark-fantasy without footholds and i was fearful that i was going to have to struggle through 500 pages of this kooky world that i just wasn't feeling off the bat. but then it broadens (oh, how it broadens) and you get to enter the story through several characters who are discovering the flexible parameters of the world along with you, the reader, and it is much smoother sailing after that. if you have a more solid background in sci-fi/fantasy than i do, you probably won't even be fazed. but i was fazed. 
 i love dark fantasy when it is set in our world, slightly tilted. my difficulty is in absorbing new fantasy-vocabulary and concepts and i have difficulty with make-believe worlds when the author has not prepared the reader enough with world-building foundations. i have to stick my fingers in the wounds to understand. fortunately, after those rocky first 30 pages, this turned into exactly my kind of dark fantasy. i'm not gonna lie - there were parts that confused the hell out of me, this is mind-bending, physics-defying stuff. but it's completely captivating, and i loved the way she built the feeling of dread throughout and dropped enough breadcrumbs for the reader to experience several "aha!" moments and to begin to see the cracks. the journey is worth the sort of dropped ending. 
 i love how into science the girls in bick's books always are. and even though their at-the-ready explanations under pressure are a little alarming and make me think i should have paid more attention in high school physics, it's great to have smart girls leading the pack through these stories. ooh-rah girl power, etc. i also love how much neurological and psychological material finds its way into her books. it puts them a nice challenging step above most YA offerings, particularly in the horror genre. 
 it's a dense book with multiple POVs and if i started talking about the actual plot, you would be as confused as i was reading those first thirty pages. the fun of this book is the journey and the discoveries, so even if i could find a way to explain the situation in a way that would make sense and not go off into hundreds of tangents, i probably wouldn't. it is dense and confusing but there are too many exciting brain-buzzy reader-chill payoff moments to dismiss it on those grounds. i will definitely read the second part, even though i know from reading bick before that she is not going to give a damn about reminding you what happened in the first book, so take notes. you will need them.