It's a fictional story and a quick read.

A guy starts talking to the home owner and convinces him that he can stay in the attic for a while. After some time another person walks into the house and the first guy manipulates the owner to accept it. Then both guys start carrying barrels with oil into the attic. They even get through a police check in by saying it's oil barrels and letting reverse psychology convince the police it's not. Then they light the barrels on fire and the home owner dies.

A notable character is the home owners wive who keeps being suspicious about the "intruders".

It was a paperback book and set maybe in the 19th century and it was written in German. I read it around 2016, while I was in highschool as part of German classes. It seemed appropriate for late teens/young adults and the main theme and focus was manipulation/social engineering.