Today is a good day.
It's a fun adventure for a slightly gonzo campaign. There's a huge iron wheel rolling across the landscape. Get inside and divert the wheel before it crushes a city.
Edit: Garbor Lux pointed out that Echoes From Formalhaut #3 also has a (smaller, non-hollow, ghost-raising) wheel. I can't deny reading the article, but I didn't remember it until Gabor pointed it out. Anyway, Echoes is well worth a read.