Many, perhaps most fantasy lands are monarchies, which can be ruled well when the monarch is a clever and able man or woman devoted to his or her people. But what happens when the monarch is ill, or is tyrannically cruel, or a young child, or is otherwise blatantly unfit to rule? How can he or she be dealt with without risking civil war as powerful nobles fight for the crown?
One of the current political paradigms of the Cosmic Era.
The plague of the Petroleum Era, the true bane of organized government
The PCs are sent with a diplomat to another country to protect him and do his bidding. There may be some espionage, rescuing, downright bullying, etc. Could make a nice medieval, special operations background.