We saw this book at the library and had to pick it up. Sofia the First is one of my daughter's favorite characters and TV shows. We're currently watching the whole series on Netflix to watch in the episodes in order - we usually catch episodes on Disney channel but they're out of order.
I had always wondered how Sofia had gotten her amulet and why she was called Sofia the First. While the TV show does have an episode where Sofia describes the King giving her the amulet as a welcoming gift, I still just felt they needed to tell the story sooner than that.
Well apparently they did - in book version. This book was published several months before the TV show first aired in January 2013. This book tells the story of Sofia coming to live in the castle and learning to get along with her new step-siblings, her step-sister in particular, and struggling to fit in with Royalty having not been born in that world. At the end of the story, you also find out how the show ended up being called Sofia the First.
If you picked this book up hoping for a more thorough plot, I could understand you being disappointed. While it does show growth between Sofia and Amber's sister relationship, there isn't a whole lot else. However, if you're reading this knowing it is the set up for the premise of the TV show, I think you'll be happy like my daughter and I were.