The book was written by Cassandra, a woman who was cursed with foresight by a god, and placed in the Books of Everyone section of the Library of the Neitherlands. When Penny Adiyodi was accidentally teleported to the Neitherlands, he came across Zelda Schiff who was holding the book. When Adiyodi asked to check out the book, Schiff instead photocopied several pages for him as she explained that she knew Adiyodi would try to take it by force but lose, and she didn't want to damage the surrounding books in the conflict.
After returning to Earth, Adiyodi and his friends used the pages to learn about the Leo Blade, a weapon strong enough to kill The Beast. Schiff later recounted reading the details of the abuse Martin had suffered by Christopher Plover when she and Kady Orloff-Diaz encountered the English Magician on the Poison World.