The Great City, Cold Crypts (2009)

From the publisher:

As you descend the wide marble stairs, the temperature drops dramatically. The air turns frigid, stinging your throat and lungs with its iciness as your breath condenses, sticking to the cold, granite walls in foggy crystals. You have entered the legendary Cold Crypts beneath Castle Atregan. Quickly you recall dozens of tales about the lightless world of ancient and terrible hauntings — how its darkness remains unblemished, for merely lighting the passages is a sin. Whispered tales come to mind of unknown fates that have befallen those mortals daring to transgress its sanctity without the proper rituals. You hope these stories are only to fill the curiosity of petulant children with dread, or to dissuade would-be thieves.

Beneath the castle Atregan lies a massive ancestral crypt, a labyrinthine tangle of thousands of tombs of ancient nobles, priests, and seers. Tales abound that the sins of centuries of Atregan rule drive restless spirits from their graves to wander the hallways in malevolent mockery.

This product expands 0one's Blueprints: The Great City, Castle Ward and the related adventure The Road to Revolution 5: The Usurpers.