From Introduction:
It seemed like the solution to all the world’s problems, Netherium. Free energy just floating all around us. Scientists able to tap into that energy to power devices of incredible wonder, changed the world. The late 1800s are a remarkable time to be alive.
Yet...some how tapping into the Netherium unleashed a hell upon the world, although the connection is still not full known. It is clear that once Netherium began to be used, dangerous ghosts, spirits, and worse came into our world.
The weakest of spirits haunt, the strongest can manifest physical bodies. Regardless of form, they seek out dark places with histories of bloodshed; castles, dungeons, prisons, or even seemingly normal place with dark pasts.
In response, professional teams of ghost hunters and monster slayers arose to combat this otherworldly menace. Some do it for the fame, some do it for the noble cause, but mostly they do it for the high fees they can charge for eradicating creatures of the night that prey on mortals.