This is the second part to the first edition. Originally they were meant to be published together but restrictions from the publishers prevented that. Book one was over a thousand pages of material originally but due to restrictions it was forced to be broken into two parts. The first book is 480 pages in print and almost 2000 in the ebook version. This edition has the complete volume of the Zodiac letters as well as all of the restored crime scene photos and more. It also includes handwriting comparisons from different events and more. Some of this is very graphic material, so an advisory label is provided. I recommend reading the first book as this was meant to be used along with it, but anyone who just wants a volume of the letters and restored/colorized crime scene photos may also find this book of interest.