Which cosmology are you using and what is the party level?
One idea you could use to change the usual composition of opponents would be to send them to Mount Celestia, in one of the upper layer. In this plane, the souls strive to be lawful-good enough to ascend to the uppermost layer, Chronias, where only law and good prevail. With the party being planeshifted, say, to Jovar, they would be technically trespassers and... would you want to be an illegal alien in a very lawful realm? They could be chased, so the players would, for once, have to fight the few good creatures in the monster manual, but they could also plead their case (as the plane is good-aligned, they won't meet only lawful-stupid paladins) and get the information they need to go down through Mertion and Solania to reach the layer of Venya, where there is a portal to the realm of Selune, where the infinite staircase sits, connecting to any city of the multiverse... and therefore home. The NPC, if he's reluctant to outright kill them, would think sending them to a good place would be "not too bad on his conscience".
The place doesn't meddle too much with magical powers so your spellcasting characters won't be nerfed too much (like they would be on concordant opposition).