The spirit of a creature trapped in amber cannot escape to it’s afterlife / next incarnation / whatever.
Such trapped spirits can be contacted by those who know the right rituals and magical power derived from them – typically the power to control one individual of that species.
Can by quite powerful if the creature is a colony insect (ant, bee, wasp, etc) – simply control the queen and you command the whole colony.
Real world scientists have accidentally opened a tear in the fabric of reality, transporting their laboratory into the game world. Unable to repair and/or refuel their equipment in this (to their minds) primitive world they are now trapped.
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.
A plague has hit the local area.
In humans it affects only the most vulnerable, the children and the very old, and even than it's little more than a summer cold. 24 hours of sniffles and then it's gone, barely noticeable really.
To sheep however it is fatal and the whole economy of the area is in serious trouble. If this keeps up the area could well be facing famine.
Somebody (enter the PCs) must find the rare herbs needed to make a cure.
A group of individuals* gather up and search for, "The rod of Lordly Might." Here's the catch, no just any individual is welcomed. There will be a meeting on sundown* in an old bar. As it is, a war is going on between the Eastern Front, and the Western Front. The bar/tavern is in the middle of both lands.
On the same night of the meeting, there's another meeting with the Red Rose (Eastern) and the Black rose (Western).
Once on the mission, there will be other individuals met and given information... there will not be an easy destiny, but nonetheless and adventure to remember.
I used INDIVIDUALS for the fact that you can be any species (just keep away from the elemental and supernatural creatures.). Here are some suggestions: Vampire/ress, Adhiel (Elf), Half-Adhiel (Half-Elf), Orc, Human, Half-Human...
Please do not be: Orc, Troll, Frost/Forest/Urban/Dessert Monsters, Giants, and Titans. Note that you can still be one, just preferably not one.
I used SUNDOWN for a realistic reason (Vamps, Giants, and others meet at night). You don't meet someone who works for the Eastern/Western Kings during the day. I expect some drunks, bar fights, and bloodshed in the story. Mild or no Language is acceptable (unless unexceptable by the MODS).