She is only allowed to fly to her destination, not anywhere else. She notices that she is not where she should be, that she cannot progress to where she was told to go, and she careens out of control when her wings won't flap anymore, and she crashes.
"Some of it seems to be by topic, and it's grouped by author but the authors seem to be in random order."
"Well, I suppose you could tell me what order the symbols go in, and then I could memorize that, and then I could squint at all the titles, but... I'm not sure it wouldn't be faster just to read all the spines."
"I'm not actually speaking your language, in case that wasn't clear, I'm just plain speaking."
"It was obvious that something more complex must be going on than you just happening to natively speak English; it wasn't obvious which of the many possibilities was operative."
Here is a book about vampires. Here is a stack of books each about another common variety of demon. Here is a book about recognizing and thwarting dark rituals. Here is a book about potionmaking. And there are more where those came from.
It's kind of obscure. A lot of assumptions about the reader's knowledge level. Also about the reader's easy access to sources of animal parts. Sherlock reads along upside-down and seems amused.
Once Promise has a general idea of what the recipes look like she skims for the results of each without bothering about how many porcupines she would have to deprive of their quills or how much marrow she would have to scrape out of a live sheep.
Potion recipes make claims to such effects as: curse removal, securing the love of the drinker for the brewer (for a duration of one month), multiplying any nonmagical liquid to fill its container (size of container unspecified but from context they seem to be thinking flagons or barrels rather than lakes or ponds), and a dozen varieties of curse including warts, plague, petrification, loss of assorted facial features, and 'to Burn with an Unquenchable Flame'.
"Except for removing a curse if someone used one of the other recipes, I can't imagine wanting any of them. Maybe mortals have discovered extremely useful liquids of some kind that need multiplication."
"I can think of a few. If I were somewhere that animal blood was very scarce, I might like to have a flask of liquid-multiplier on hand. But yeah, a lot of old magic is primarily concerned with doing nasty things to one's enemies."
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.
"It's good advice, if you ever plan to get on the wrong side of the sort of person who does dark rituals."