The Man From Before

From the designer:

A mountain village grows wealthy selling a strange and magical oil. But its prosperity is tied up in the legacy of a fateful war. Only the children know the cost of the work they do—at the bidding of the Man from Before.

I can't even explain this one. On the surface, it's a pastoral mystery, suitable for low-level adventurers. Scratch that surface and there's an extremely powerful NPC, possibly an ally or mentor. Or, maybe the players will see the dynamic as monstrously exploitative and view him as a villain. Push a little harder, and there's a campaign-wrecking bomb, just waiting to go off.