“ Whilst exploring underground the PCs discover tube like tunnels stretching for miles, upon further inspection the strange tunnels seem to connect all major cities in the are, what is their purpose?”
“ Adventurers are to capture an unknown monster for examination (for a sage or wizard) but they are themselves captured by the monsters, and researched.”
“ A rather large armed group slowly walks the road. Unless you get to see what they transport, you could think it is a caravan with expensive goods, or the soldiers escort someone important. But this is a prisoner transport, on the way to mines, criminals on their way for punishment.
The soldiers may be willing to talk, the captain will have a few questions on you and the road, but they will keep distance, and part soon.”