There are some books that I've read before that contains the element of taking a character who has been away from regular society for a long period of time (if ever) and sticking them back in (bonus points for making it smack into the middle of high school). I've seen this done really poorly and I've read books where I'm basically getting really angry at the author for just using it as a plot device and not tackling the genuine psychological scars and struggles that this character would go through.
I'm please to say that Murdoch handles this topic supremely well, in my opinion. Carey reminds me a bit of Katniss Everdeen from [b:The Hunger Games|2767052|The Hunger Games (The Hunger Games #1)|Suzanne Collins|https://d202m5krfqbpi5.cloudfront.net/books/1358275334s/2767052.jpg|2792775] with her intelligence, determination and fierce protectiveness of her little sister, and in fact, the book allows for showing this transition for both characters: the more innocent and affectionate Nessa and the wary and think-things-through Carey. These are girls who have developed their own method of survival for a life eons away from regular society and their new attempts to adapt are very, very real. Their story is heartbreaking, but holds the glimmer of light on the horizon. A beautiful story.