This is inspired in part by a thread on YSDC.
For those who aren't familiar with the setting, Bookhounds is a 1930s era campaign book for the Trail of Cthulhu horror RPG. The concept is, the characters are traders in antiquarian tomes of one kind or another, particularly occult or outre grimoires, and they get their daily bread by trading in knowledge that man was not meant to know. It's a fine line: do you opt for poverty and refuse to sell to the sinister gentleman who may have very dangerous ideas, or do you damn the consequences and hope it all comes out all right in the end? Perhaps you opt for an even more dangerous game, and forge realistic looking tomes for sale to the highest bidder. The setting lends itself to M.R. Jamesian spook stories (many of his protagonists were antiquarians, and not a few found themselves in awful trouble because of a dusty old book) and has an atmosphere that's part Lovejoy and part Club Dumas.
The question is, what to do with it? Bookhounds is an impressive toybox, but can leave even veteran keepers feeling overwhelmed. As a setting, it's very nearly unique; plenty of games have horror elements and London certainly has been used before, but the antiquarian book trade is something altogether other. Most RPGs assume that the protagonists are Heroes with a Capital Haitch, and while Cthulhu tends towards the weedy academic side of the street even so there's usually one or two brutish toughs in the group. This time everyone's a cultured sort of gent who wouldn't dream of dirtying their knuckles - not when they can pay someone else to do it for them, at any rate. How do you set up a campaign with that sort of group?
Well, the obvious first step is to pick an antagonist. The essence of the setting is trade: the characters are buying and selling knowledge. Therefore the antagonist is going to be someone interested in that knowledge.
This is slightly different from the average Cthulhuoid plot, in which a disparate group of loons get drafted in by dear old pal X to globetrot around the world (see also Masks of Nyarlathotep, Horror on the Orient Express) fighting cults or helping stop the awakening of Old One [fill in the blank]. This time out there is no dear old pal X nor is there necessarily a global conspiracy. There's just the trade, and most of the action will be taking place in one location, London.
So let's start out by designing that one antagonist whose actions will spur the plot along: the customer. [S]he may or may not be mortal, or human. That said, there has to be power here, and a lot of it, for two reasons. First, without power there is no real conflict: the characters will probably be able to foil the evil schemes of a hobo living in the back alley behind the shop. Second, without power there's no real reason to worry. Even if the hobo's machinations aren't stopped, they can probably be ignored.
There also has to be an overarching goal for the antagonist. [S]he wants knowledge; if not, there'd be no reason to do business with the characters. There must be a reason for wanting that knowledge. Perhaps they want more power, or immortality, or to create some lasting monument to their God (or themselves, if they're going the Carnegie route). Whatever it may be, it is a concrete goal which they can only achieve by using occult means.
With those two facts in mind, let's brainstorm.
Assume a very wealthy widow, Sarah Montgomery, who lost her two sons in the Great War, wants to recreate the world that she believes was lost when the Guns of August started firing. She doesn't just want her sons back; she wants to remake everything as though the First World War had never happened. Because she has dabbled in spiritualism she came into contact with someone steeped in Mythos knowledge, Stanley David Fentiman, ex-Oxford don, who has a different goal in mind: he wants to recreate the school of black magic that existed at Chorazin, once upon a time, and set himself up as its new (immortal) headmaster. Fentiman is using Montgomery's money and connections to get the knowledge he needs, and in exchange he's promised to help her get what she wants.
Here you have two antagonists with very different goals working together. One is motivated by grief and loss, the other by a lust for power and immortality. In each case the motives are human and understandable, but in order to achieve their goals both will have to steep themselves in Mythos knowledge.
Which is where the characters come in. At first they may only know about Sarah Montgomery, and they may not even meet her face to face. After all, someone as wealthy as her can afford to hire agents to do their work for them. However they will be drawn into her schemes by her continuing search for Mythos knowledge, and in the process of uncovering books for her they'll reveal her overarching goal. Who knows? They may even agree with her, that the world would be better off if the War never happened. That said, the methods she's using to get what she wants are highly questionable, and could lead to disaster. She'll be drawing on the powers of the Old Ones to do what she intends, and that can only lead to trouble. Is her plan even feasable, or has Fentiman lied to her to get her to finance the project?
This could easily turn into a two-pronged campaign. The opening act would introduce the characters to the world, and to Sarah Montgomery. The second act would reveal Montgomery's plotline, and have the characters attempt to foil it, or perhaps pick up the pieces when it all comes crashing down around her ears. The final act would be a race against time to stop Fentiman, before he does something that will change the world forever. More on that kind of campaign design later.
For the moment, consider this: you oughtn't to start a campaign by wondering what kind of threat to fling at the players. You ought to start by thinking about your antagonist: what do they have, and what do they want? For it's the antagonist that will drive the plot, and whose actions the characters will have to react to. Without a good antagonist, you can't have a good game.
That's it for the moment! More to come.