* At SOME POINT during the campaign, you should choose one of the major NPCs to be the black cowl. I waited until book three and implicated all three throughout the entire campaign until the bitter, bitter end. I chose Marcus Bauerfast.
* You start in Averland at the docks, investigating some things and then helping out some merchants in a menagerie party. There are a LOT of rumors floating around and several avenues of interest to follow. You will face standard creatures here (and even some kind of rumored tailed creatures from the sewers)
* There is some travel and some encounters
* Then you move to Middenheim where there is some more investigation and a trial of a man you can't figure out if is guilty. Lots of NPCs, not much monsters.
* Book 3 is in Altdorf, where all kinds of stuff with nobles happens, including more investigation and culmination of the campaign (IMHO)
* Book 4 you can chase the Black Cowl (b/c you have to have him get away if you want to play this section) and you travel to the chaos wastes and chaos realms. This part is highly underdeveloped and I have chosen not to run it (sadly
It has all kinds of creatures and stuff, but is primarily investigation with a lot of human opponents and LOTS of skill checks rather than "just murdering stuff to be told the solution of the mystery," which I had grown tired of in other games (cough..Pathfinder..cough..D&D)
I think my players enjoyed it.