That's a very good point, and, of course, if anyone has it (or can acquire a copy) the Cairo Guidebook is very useful as well. I will also mention, in passing that Ken Hite wrote up something for pulp play called Tombhounds of Egypt which is based off the same system used in Trail of Cthulhu and can be useful for both atmosphere and some ideas for a Cairo-based campaign. (And PoC and someone else previously mentioned Amelia Peabody's Egypt as a good source book -- which I have since acquired and can definitely agree that it is.)
I would like to note that it's past time for Chaosium to consider updating things like the Cairo Guidebook, however!
Also, on the London chapter, I can't recommend Cubicle 7's Cthulhu Britannica: London highly enough. It's a superb boxed set giving some wonderful background info and a LOT of detail on day-to-day life, historical events, myths and legends, etc., all of which will add some superb atmosphere to your London adventures. And the maps are fantastic! Of course, there is also the older London Guidebook and Green and Pleasant Land (which has a brief description of London, among many other places). Finally, there is Pagan Publishing's Bookhounds of London, a campaign setting for Trail of Cthulhu, which, while grittier than some, does have a lot of interesting information in it as well. It should be noted however that there is a lot of overlap among all these sources; so if I had to recommend but one, it would be Cthulhu Britannica: London as a primary source book.
As far as New York goes, of course, there is Secrets of New York, which is helpful, and Tales of the Sleepless City (Miskatonic Press) adds a bit of depth to the city -- as well as a number of scenarios that might conceivably be adapted for use in the campaign as well.
If you're considering playing the "pre-scenario" where the players meet Jack in Latin America, I can recommend Pagan Publishing's The Mysteries of Mesoamerica as a good source book (not "superb," but definitely quite good). And, at least one of the scenarios would be easily used for the same purpose (introducing Jack to the players) as the one included in the Companion, if you wanted to throw a curve ball at anyone who has read the Companion already.
Edited by jlynn, 21 September 2017 - 05:51 PM.