Cuckoo Song by Frances Hardinge
Published by Pan Macmillan, May 2014 (UK); Amulet Books, May 2015 (US)
Publisher's description: 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 . . .