Staired in Horror

A ruthless killer is on the run, and hard on his heels are officers of the law with a tracker dog. He turns up at an isolated house, the sole inhabitant of which is a woman who is so old she might have come out of the Ark. Spinning her a tall tale, he convinces her to hide him, which she does even when the truth becomes apparent. And how does he show his gratitude?

Well, at one point he is about to murder her, but she talks him out of it and goes upstairs where she is replaced by a beautiful young woman. This is where the real problems start, because she cannot come down the stairs and he cannot ascend them, not without something bizarre and horrible happening. They decide to meet halfway, but at this point the posse returns and he is forced to ascend the stairs anyway. What happens next is not a pleasant sight, but most people will agree it couldn't happen to a nicer guy.