"Hinter den Schleiern" ("Beyond the Veils") is a publication in the series "Cthuloide Welten Bibliothek" which is an offspring of the german "Cthuloide Welten" magazine by Pegasus Spiele, containing four scenarios in different settings for the Cthulhu RPG.
From the publishers website (translated):
"Beyond the Veils" contains a background part "Cthulhu 1200 AD" as an expansion to "Cthulhu 1000 AD" plus four scenarios for different eras and settings.
Cthulhu 1200 AD - Baphomet's Circle
The investigators search the sieged city of Constantinople in the Middle Ages for the Al Azif, the original Necronomicon, threatend by fanatic templar knights and others.
Cthulhu WildWest, 1890s, 1920s - The Golden Scorpion
An ancient treasure map shows the way to a long forgotten aztec temple, where not only the Golden Scorpion, and invaluable treasure, is supposed to be found, but where also the life of the investigators will change radically.
Cathulhu - The Trail of the Black Cats
More and more cats are getting murdered in Arkham, and the killer appears to be a horrible beast. The furry characters start to investigate this mysterious case.
Cthulhu Now - Project Pi
As hardened Navy SEALs the characters explore a ghost ship, discover the horrible truth about the fate of the crew and even enter sunken R'lyeh itself. Cthulhu fhtagn!