On the Third Day (Movie)

A headmaster and his wife return home to find one of their doors to have part of a window pane neatly cut. Looking through the house for whatever might be missing, they find a young man sitting in one of their rooms, and the phone isn't working. The man's behaviour is strange, but polite. He says he's arrived from Australia and was friends there with an old friend of the headmaster. He proves to have a lot of personal knowledge about the family, so his story seems to be true. However, he definitely has a dark side, doing over-the-top "practical jokes," producing a gun, engaging in a particularly bloody boxing match. (IMDB)