The Standing Stone, adventure for D&D 3rd/3.5th ed, by John D. Rateliff.
“What terror stalks the villagers of Ossington? Who is the ghostly horseman haunting the road, stopping anyone from leaving? Why are the wild elves slaying villagers from afar with their deadly stone-tipped arrows? What lies buried in the old Great Barrow, and why is it stirring anew? What secret do the ancient standing stones surrounding the village hold, and can the heroes solve the mystery before a foul plot comes to fruition?”
Stand-alone adventure for 7th level characters.