This book gives you more detailed information on the Werewolfs biggest foe: The Wyrm
From the back of the Book:
"Book of the Wyrm includes:
- Detailed information on the Black Spiral Dancers, the hideous "lost tribe" of the Garou.
- The subsidiaries of Pentex Incorporated and their machinations for power and conquest.
- Traits and rules for hordes of creatures, Banes, fomori, dread Incarna and many more minions of the Wyrm."