Incarceron by Catherine Fisher
Set in a world where progress has been effectively and artificially halted at late medieval period in order to protect society from the evils of technology, Incarceron follows two teens from the most divergent of circumstances.
Finn is a 17 year-old living inside Incarceron, a vast intelligent prison that has been sealed for more than a century. Intended to be a utopia for the unsavory elements of society (criminals, madmen, the poor), Incarceron is nothing like those outside believe it to be: more hell than paradise. Though Finn is believed to be cell-born (born of the prison, which recycles everything including organic matter), Finn has no memory older than three years.
Claudia is the cossetted daughter of the cold and remote Warden of Incarceron. A bright girl who rebels against the restrictions society (and her father) places on her, Claudia is doing everything she can to delay her marriage to the unsavory crown prince.
I finally finished Incarceron. It took me a long time because I had to get back onto the waiting list for the e-audiobook when I didn't finish the book during my first check-out period. I didn't know much about the novel before I started listening to it and I have to admit that I was disoriented at first (Fisher really throws readers right into the middle of things). As the two stories progressed, however, I became invested in both of the protagonists. I'm already on the waiting list for the sequel, Sapphique.