This is my most recent draft of a not-entirely-abandoned estate that my weekly D&D gaming group came across while searching for a party member's missing father.

The party of adventurers discovered this manor house hidden within a magical veil of mist. They would soon discover that the mist marks a boundary between the physical and spiritual worlds, and what lies inside the manor are tormented spirits, magical traps, and horrific experiments left behind by the demon cult that abandoned the estate long ago. However, someone not among the dead still uses the estate and the energies surrounding it to fuel his own dark plans, which include using the party as pawns in a conflict started over a thousand years ago.