Knocking, coming from inside the walls, kept them awake at night. It was often freezing inside the trailer, though the furnace was inspected and found to be in perfect shape. Shadows flitted in their peripheral vision. The parents became so frightened, they decided something needed to be done.
The father's mother came in one sunny afternoon and blessed the place with holy water. She went through each room, water and crucifix in hand, casting out negative influences. After she finished, the furnace kicked on and the trailer finally became warm.
While ghosts/strange happenings weren't uncommon on the farm and its buildings, nothing sinister or scary occurred for years onwards. Then, around the turn of the millennium, knocking again started in the walls.
By 2001, the father's sister and her three children had lived in the trailer for about a decade. They all heard the knocks, but they attempted to ignore them.
"Just tell them to go away. Don't invite them in," the mother said. And the children (who were two young adults and a teen) agreed.
One night, the mother's six-year-old nephew was there when the knocks came. One... two... three. A pause. And again, one... two... three. A slow repeat. The mother and her children told the nephew at various points to ignore the knocking. He looked at his teenage cousin (a girl) with glee and shouted, "Come in! Come in!"
The knocking stopped abruptly.
If you want, I'll continue the story next week. I don't want to keep going if no one finds this interesting. I know it's written as a regular post and not a short story.