From publisher blurb:
There has been corruption under the Eerie Forest for a long time, so long ago that the ancient people built a stone circle and barrow to imprison it. The corruption brooded while armies of goblinoids raged across the land and then one simple act of treachery gave it the chance it needed to manifest again. There is now a monster lurking in that ancient ring of stones, preying on anyone foolish enough to indulge in tomb-robbing and it needs to be put down. The characters have to enter the barrow and learn how the corruption got a foothold and find themselves an ally.
This adventure is designed for four characters of 4th level in the Fifth Edition of the world’s oldest roleplaying game but can be easily adapted to higher levels.