As a fan of Holly Black's work & having seen the movie based on this book I started wondering why I had never read the book.I love the fact that the movie was so close the book. The Field Guide is just an introductory book to the Grace brother's & their story. And nothing said in them differs from what appears in the movie, which is great.Overall, i would say that if you liked the movie you definitely need to read this one. But that it's shortness will leave you begging for the next.