A land is reigned by a circle of powerful men who control every aspect of the citizen's life. This cabal changes members often. In reality, the spectres of a small necromantic covent possess and control the people in power. Since they simply possess the bodies, they can leave when old age overcomes their shells and possess a new up-and-coming noble.
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...