It was an older color movie, I saw it on netflix a long time ago. It was about a strange family consisting of a brother, sister, and mother living in a mansion. I don’t remember if there was anybody else living at said mansion. Anyway, one night (I think it was at night I could be wrong) the two siblings go out beyond their property and run into a man and woman. They start playing with the two and eventually end up killing the woman with the guy ending up at their mansion. I don’t remember much beyond that.