In this book, the blues scale is taken through all possible fingerings in the one key, making it possible to play fluently over the entire range of the guitar.
Other keys are introduced later in the book, but only after the fretboard has been mastered.
The central approach of the book is the development of musical technique. Although many new scales, arpeggios and techniques are introduced, the emphasis here is on how to really get the most out of the notes you play.