"Dartmoor" is an original german scenario for the Cthulhu RPG published by Fantastische Spiele GbR.
From the back of the book (translated):
A horrible murder strikes the city of Exeter. The sunny fall of the year 1920 shouldn't raise such dark thoughts normally. A young lawyer gets the surprising chance to execute the last will of the victim. This simple task leads the investigators to the bounds of their own self. From the mortuary in Exeter it is a long way to the swamp plains of Dartmoor. And isn't that the direful silhouette of Dartmoor Prison reaching out of the mist?