From the back of the book:
Stalk night's black agents: the Assassins. Armed with the secret lore of this new adventuring profession, players become the shadow warriors, the silent killers of the dark, who pass unseen and bring death by poison, knife of lethal throwing spike.
Out of the Shadows presents the full rules for Assassins - techniques of stealth and the martial arts as well as arcane alchemy, mysterious trance-magic and the unstoppable power of the DEATH VOW. Also included in this book are more than fifty new terrifying monsters, special combat expertise and magic for high-ranking characters, and three enthralling adventure scenarios.