I thought I'd talk about books in Trail instead.
Bookhounds of London is one of those settings that wants a lot of input from the Keeper to make it really flow, if for no other reason than the Keeper doesn't have enough books available. Think about it: the characters track down and sell books for a living, and unless it's a very one-note game they can't be after the Necronomicon every week. The Trail main book has about seventeen Mythos tomes, and Bookhounds includes ten more occult tomes, seven Mythos books and guidelines for making more. No matter what style of game you run you're going to need some home-brewed books for your Hounds to chase after. Plus, unless you're the sort that only ever wants to play Arabesque, you're probably going to want to at least consider the various play styles each time you create a book, or an NPC. That means a little more effort on your part.
When faced with problems like these, I always go back to history for answers. There have been any number of odd beliefs, rituals, purges and persecutions in the few thousand years we've been recording our time on this planet. These can be mined for scenario information, and the big advanatage is it avoids repetition. I recently bought a copy of Gary Myers' House of the Worm, which I enjoyed, but it does repeat itself again and again. You could summarise most of the tales in that book: 'dude gets in over his head, dude dies or goes missing in weird and mysterious way.' Fun, but one-note, and the thing to bear in mind is we all have a one-note tendency. I know I use dream sequences a lot in my work. I tend to like spook stories as well, and use Gothic effects more often than not. It would be so very easy to rely on those same elements again and again, never experimenting, never going outside of my comfort zone. History forces the writer to look outside his front door, to see the world in all its varied glories. It forces experimentation with new settings, ideas, adversaries and conflicts.
In this instance I used some facts culled from Montague Summers and got translation help from Babelfish. This is what I came up with:
Ein Konto der Hexeraserei im Lindheim
An early modern Mysterious Manuscript for Trail of Cthulhu.
Edit: as luck would have it, this item is to be printed in the Unspeakable Oath, issue #21. I don't think that edition is out on general release yet, but I have received a .pdf contributor's copy. It would be unfair to Pagan to have this item here on the blog, and after discussion with the Oath's editorial staff I have agreed to remove the description. Once issue #21 is out I will link to it from here; for now, I hope you don't mind the inconvenience!
Summers is one of those authors who can be relied on for the weird and wonderful. I don't think I would rely on him as a historian, but I respect his mastery of the source material. In this particular instance I was using his book on witchcraft which tends to be easy to come by. In fact most of his books drift in and out of print, and while you're unlikely to find them in Barnes and Noble they're worth tracking down, as he's always good for a quote or two. Probably a foaming-at-the-mouth sort of quote, but nevertheless he's good value for money.
Witchcraft is a phenomena that, in Europe, seems to peak at about the same time as the major wars of religion are being fought, which probably isn't coincidental. Any number of firebrands and nutjobs are roaming around looking for a fight; these are people who, in their day, would have been the equivalent of a Bin Laden, but whose names and lives have been almost forgotten. The world was teetering on the brink of disaster (again), powerful kingdoms were busy toppling their neighbours' regimes (again) and innocents were being massacred in their thousands (again). There would have been many people like Geiss using the situation for their own benefit, taking advantage of the fact that what passed for central authority was weak and constant warfare had everyone on edge. He wouldn't have had to do much talking to convince his neighbours that the enemy walked among them; after all, panics, plagues and strife had been all they'd known since the days of their grandfather's grandfather. In conditions like those it was very easy to believe that they weren't safe yet, that there were those who followed heretical religions or who were plotting to do them harm.
Once you have that central idea, everything else is window dressing. I freely admit that Wikipedia has been good to me; it's allowed me to check names, places, and dates. But knowing what to look for is critical; knowing that the Great War of 1914-18 knocked out a lot of the old Grand Dutchies, that there is such a thing as an octavo, that people used maker's marks, all adds to the feeling of legitimacy. Arturo Pérez-Reverte Gutiérrez managed something with Club Dumas that Lovecraft never did: he made the Nine Gates of the Kingdom of Shadows seem as if it were real, not by adding extra bookworms gnawing at the pages or more elaborate olde Englishe script, but by adding enough real data to the description of the Nine Gates and its all-important illustrations that it didn't strike a wrong note once. That's the kind of thing to aim for!
Now, I've talked too much. Next time I will discuss hauntings, I promise!