A book bound in leather cured from the faces of men and women, their agony forever preserved in the screams of pain that now adorn the book’s hideous cover. A book whose touch burns flesh.
A book written in Arabic on the planet Earth by a man later torn apart on the streets of Damascus. A book discovered, and then translated into Greek. A book whose second owner was burnt alive in Constantinople. A book hidden in the Dreaming, and then re-discovered by an agent of the Whispering Tyrant and carried finally into Golarion, where it was translated once again, this time into the Necril tongue.
A book that has broken minds and destroyed souls.
In Chapter 99, the party met the Yellow King, who claimed that he had been created as a shard of Count Haserton Pragmus Lowls IV, who shattered when the Mad Poet showed him this book.
In Chapter 150 (Part 2), the book was revealed to be a version of the legendary Necronomicon, and that another version of it exists on Golarion.
First Reference: Act II Interlude
Other Notable References: Chapter 99, Chapter 150 (Part 2)