So, you've agreed to run a game today and you have not had time to even think about an adventure. Don't freak out. We have you covered. This document is all that you need. Run this adventure. It will be over in one session. Then you can get back to your own evil machinations next session.
While this adventure is set in the Boot Hell campaign setting, it can easily be used in any sort of Western steampunk or horror roleplaying game. It uses 5th Edition SRD rules as a default.