This book, like the others, uses the artwork during the development of the film to retell the story. Those familiar with Mary's artwork know that her drawings are simple, but at the same time, richly detailed. The text of the book is written by Dave Barry and Ridley Pearson. Most likely chosen to tie-in with the latest release in the Peter and the Star Catchers series.
Of course, if you're a huge fan of Mary Blair, there's also her biography, The Art and Flair of Mary Blair.