Ochre-robed pilgrims started buying swampland around Overlord City. It was more than bad business to Shyath Syrus, Arch-priest of Mitra. He knew what was buried the flood plains outside Haghill, and he knew the stakes.
Syrus sent a party of adventurers to the site of an old moat house, recently purchased by the mysterious pilgrims. The ruins above were quiet, but dark rituals were playing-out below.
After dealing with cultists, and the remnant horrors of the moat house dungeons. The party stumbled upon a giant black obelisk; the first of many to be discovered in the coming years.