"They said it would bring us a new age of wonder, of exploration, of excitement. I don't think this is what they meant: us scurrying around like rats in our cities of steam and steel, far away from the land and the sun."
An industrious colony of Gnomes have managed to turn a hostile environment into a bread basket.
The People of the pocket realm of Brocschtal are simple folk who live as they have for thousands of years. Farming the land, raising sheep, getting in the occasional brawl. And fighting off the infernal attacks of ghouls.
They should have spoken up sooner and saved poor Harold from certain embarrassment.
The world was ripped apart in a great cataclysm 3,000 years ago. This is a Codex of the pocket realms created by that great sundering.
Three cities that come and go, yet never see the shining sun.
The Imperial city has been sucked into hell and the rest of the world has been ripped apart. And tying it all together is the Crystal Tower. The Tower lives in all realms, a needle piercing the fabric of each reality and threading them all together.
The PCs are accosted in a major city containing at least one famous fortuneteller / prophet of the future. They are informed that their as-yet-unborn child will (insert terrible evil), and that, although they are very sorry, the PC must be executed to keep this from happening.