I was really enjoying this book and was leaning towards four stars, but about 75-80% of the way through the book Mackenna just got so annoying the way she kept trying to run away or escape and she wouldn't just trust Thomas after everything he had already done.  She just kept making everything unnecessarily worse.  And then the ending kind of just happened.  It wasn't a bad book, but it was really unsatisfying given how enjoyable the first half was.