From The Introduction:
The Depression is hard on everyone, but it’s hardest on the bookhounds. Not that there aren’t books out there to be had: baronets and bishops alike are selling off whole libraries now that cash is short. Not that there aren’t buyers for the specialised volumes: Eton-and-Oxford aristocrats willing to try anything as long as it’s vicious; sweaty would-be Great Beasts looking for the shortest path to demonic power or at least to devilish orgies. Between those two groups, sellers and buyers, a specialty market has sprung up in black magic and blasphemous tomes, no questions asked.