What Belongs to Darkness (German: Die Finsternis und ihr Eigentum) is a 1922 German silent drama film directed by Martin Hartwig and starring Karl Etlinger, Erra Bognar, and Fritz Kortner. The film's sets were designed by the art director Alfred Columbus.

Blanche Benton is out on her morning ride with horse and carriage, when an automobile shows up and scares the horse. The driver in the car manages to intervene and takes Blanche to her home.

The young Evelyne lives with a man, her fiancee Frank, with whom she has a child. But her fiancee is a rundown drunk constantly hanging over the bottle. Evelyne wants to leave Frank.

Railway employee Fritz Marr is not regarded well by his superiors. It is the year 1920, and trains regularly pass the railway hub of Erfurt to the East to secretly transport weapons for the fight against the young Soviet Union. Marr knows about this and wants to mobilise other workers to stop these illegal deliveries. To muzzle him, Marr is relocated to a remote rail work construction site.