the dementor's

You are a Ghost hunter and today you are going to an abandoned house because they called you to expel the Ghost, when they leave you alone in the house you walk through the abandoned house listening to every noise as you walk you feel a presence as if you were not alone in the house. .. and when you go up the stairs and enter a room you feel that the door closes and a supernatural force grabs you by the neck and puts you against the wall tightly, when you look up you realize that it is a ghost, a dementor... the ghost says with a sinister and cold voice
"What are you doing here, mere mortal?"

A ghost is in an abandoned house and it is your job to expel him from the house to give peace to the place...