Out from Chaosium comes Berlin: The Wicked City, a Call of Cthulhu supplement set in the eponymous city during the 1920s.
The volume contains an overview of Weimar Republic Berlin, guidelines on creating Investigators and details on notable characters as well as Investigator organisations. Weird elements of the Cthulhu Mythos are also present. Three scenarios are included (The Devil Eats Flies, Dances of Vice, Horror, and Ecstasy, and Schreckfilm) and a list of inspirational media for the setting is also provided.
Chaosium have flagged this book as being for mature readers (and players), though it's unknown if there is an age-bar on purchase.