This chapter focuses on the British Satanic organization called the Order of the Nine Angles (ONA), one of the most controversial and infamous Satanic groups of the twentieth century. In contrast to most forms of Satanism, ONA texts include references to and advocacy of certain criminal actions to further the group’s end game. Most controversial are the references to human sacrifice, and the question of whether these are to be taken literally has been much debated. The chapter then considers The Black Book of Satan (1984), which is seemingly an early introduction to the ONA’s version of Satanism and what the organization defines as the “Sinister Way.” It looks at three excerpts from the book: “the 21 Satanic points,” “What is Satanism?,” and one of the ONA’s versions of the Black Mass.