The Mad Mechanist
This is the beginning of the adventure I had in mind. It can be adjusted for other settings, however. The PCs are traveling from one large city to another. Along the way, they come across a small covered wagon, abandoned by the side of the road. A search check (DC: 10) reveals a stack of paper tucked under some blankets inside the wagon. The stack of paper is a shipping manifest from a scrapyard to three factories in the capital. Outside the wagon, clear ruts from wagon wheels are visible, leading off road to the west. A search check (DC:20) reveals humanoid footprints heading off west with the wagon ruts.