S1·E46 Dame Elaine

Moominpappa has inherited a real castle from a distant relative. He doesn't really want to accept the inheritance, but when he learns that ghosts are haunting the castle, he changes his mind. No monster awaits him as the castle ghost, but rather Lady Ellen, who has been inhabiting the old walls for seven centuries now. So it's no surprise that the gracefully floating night ghost is a real chatterbox, looking for someone to talk to.