All of the characters are somehow connected to a creepy old house in or near their neighborhood. Some ideas: you are squatting there; you just inherited it from a mysterious grandma or aunt; you are obsessed with its odd architecture; you are a ghost-hunter who had an experience there you need to understand; on a dare you slept a night there as a kid and woke up as an adult; etc.
The house is a strange place. Its architecture is indeterminate, but vaguely historical. There are times when the rooms and layout do not seem to be quite consistent. People don’t always notice that it’s there, even though it doesn’t fit with the other nearby homes, but when its mentioned, a lot of people have a story that involves the house.
It’s a big house, with at least five bedrooms and a few other rooms like an actual, honest-to-God library. There is a basement and attic, visible because you can see the old style storm doors that lead down and the circular upper windows.
It has been a long time since someone took care of the place. The yard is overgrown and spotty and the trees are huge and sweeping with moss and branches overhanging the roof. It is set a bit back from the street with a circular, gravel driveway and an old garage.