The City of Strangers. The Beautiful City. The City of Gold. The City of Sharks.
A dangerous, alien plane where glowing frog-slimes slither and slurp, metal-skinned bird people rebuff diplomacy, and only the endless subterranean tunnels are safe (just mind the gravity-bending moles). Visitors will have to skulk around in the dark to avoid the curse carried by the sunlight. Because (have I mentioned?) the sun is the source of a powerful curse--one that covers the whole planet.
Mondaloa is a name shared by both a city and a deity. Mondaloa, the city, is built on layers of crypts and tombs that are far more opulent and majestic than the city that covers them. Mondaloa, the deity, is the god of rest, peace, and death. There is nothing Mondaloa desires more than to see the dead buried deep in their tombs where they can rest in honor and peace. But there is trouble: something is torturing the dead of the city, and driving them to madness and rage. Now, 500 years of honored ancestors are trickling into the city above, seeking blood and pain and death.
The PCs are walking along the road, when suddenly a bunch of bandits attacks. The player's dismiss it has just a random encounter, when they find an ornate ring on the leader, obviously out of place with the seemingly poor bandits, who could only afford cheap leather and weapons. This ring has a symbol on it, which, if researched, sets the PCs on a quest. And from then on, the players don't look at random encounters the same way...