Ok, so this isn't a TRUE pre pub book buzz because it's been out in the UK (and available through international resources) for a while. BUT it's been nominated for the inaugural James Herbert Award (along with some other fabulous horror titles) and the good folks over at Amulet Books are releasing a US edition in May.
Here's a bit about the book from Goodreads for you:
When Triss wakes up after an accident, she knows something is very wrong. She is insatiably hungry, her sister seems scared of her, and her parents whisper behind closed doors. She looks through her diary to try to remember, but the pages have been ripped out. Soon Triss discovers that what happened to her is more strange and terrible than she could ever have imagined, and that she is quite literally not herself. In a quest to find the truth she must travel into the terrifying underbelly of the city to meet a twisted architect who has dark designs on her family-before it's too late . . .
Set in England after World War I, this is a brilliantly creepy but ultimately loving story of the relationship between two sisters who have to band together against a world where nothing is as it seems.
I've actually read some reviews of this (like this one from The Midnight Garden) and it seems to live up to the excellent description here. I'm dying to read it (and the rest of the award nominees I've not yet read as well).