Two Hours with a Madman

On a long journey, the narrator is caught by sunset before reaching home, and so stops at a nearby farm and requests lodging for the night. The narrator is visited during the night by a madman who claims to be from a graveyard and looking for a companion. Just barely escaping death, the farmer and his son come to the rescue and explain that the madman is a brother-in-law who has crazy episodes during certain phases of the moon.