Nerundill caught hints, snippets of conversation. The rumors surrounded a book, a book of magnificent power. A book that contained the knowledge of the ancients. With every new tantalizing bit of information he heard, his resolve to possess this book increased.
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....)