In the mist outside Seversk, there is the Volkonskaya Manor.
The owner of the manor is an eccentric girl detective. She rarely leaves this area. She only travels by carriage, and her range of activities is no more than an hour's journey by carriage. The cases she takes on are not big: things are lost in the town, disputes between neighbors, trivial matters that the police cannot find out - but every truth she uncovers is hidden in the dust and scratches that others ignore.
The new assistant came for money, but found that the manor was heavier than any case: there were cries deep in the walls, old letters were locked in the tower, the previous assistant died in the woods, and the owner of the manor seemed to be trapped in an invisible net, unable to step out.
The fog here stays all year round. But things in the fog will emerge sooner or later.