Berlin - The Wicked City: Call of Cthulhu 7th Ed - Rules of Play says:
This book presents an overview of 1920s Berlin as it would be experienced by visitors and residents of the time. Guidelines are presented for creating investigators for a Berlin-centric campaign, as well as investigator organizations to help bind groups together. Notable personalities, key locations, and a system for generating details of the urban landscape on the fly are provided. With crime and punishment, the city’s underworld, and also its high culture detailed, the tools provided help the Keeper gain an understanding of what makes Berlin unique. Three scenarios, spanning the history of Berlin between the end of the Great War and the rise of Adolf Hitler and the Nazi Party, contain colorful details of Berlin and its inhabitants and may be run as stand-alone adventures or linked together to form a mini-campaign.