Dark rituals are primarily concerned with doing nasty things to one's enemies! The book offers a variety of signs that a dark ritual may be going on nearby, recommends several effective ways to thwart one, and advises that you do so anonymously if possible because the kind of person who does dark rituals usually doesn't appreciate being interrupted.

There's a densely-written page and a half of advice on ensuring that you can't be easily traced: don't let them see your face; don't let them hear your name (where 'yours' is any you commonly use); keep very good track of your hair, fingernail clippings, blood, etc.; do not lose any items of sentimental value near a dark ritual site; if you suspect you may have lost a glove, sock, shoe, or other paired garment near a dark ritual site, burn or abandon the remaining item immediately.

"Very thorough," comments Sherlock regarding these safety measures.