"Catch Me When You Can"

My Jack the Ripper scenario for Call of Cthulhu is starting to take form. I've got a near-complete list of possible PCs. I'm still chewing over whether to include a cop or not. I've got a mthod for getting the group together, charging them with their mission, and putting them on the track of the Mythos. I've got at least one good lead to put them on to. I've got one or two surprises lined up. Most importantly, I've come to a firm decision as to the identity of Saucy Jack. I need a few good places to set some encounters, and maybe a lair that the PCs can suss the Ripper out of. You know, a dungeon. Also, I need to start statting out all these folks.