"Hey there, you look like a sturdy fellow! Interested in a treasure map? Only a few gold coins and this map to an ancient ruins secret room can be yours!"
A Basic Dungeon Crawl that starts with a map.
You receive a vision of a rooftop "somewhere close by", where a rare moss grows; in the vision, you know the moss is suitable for greatly enhancing the effects of certain types of potions. Now go and find that rooftop. Don't fall off. (Of course, rooftop runners *will* be taken for miscreants by the local City Watch....)