What has happened to the Queen of Quumla?
Each of the Ten Queendoms has their own ritual of succession, but in none of them does it involve the queen simply disappearing. But that is what has happened in Quumla.
In the case of a Queen dying without having chosen her successor, the High Council selects the next Queen, usually from among their own number, and usually a human. However, the Queen is not definitively dead. And the High Council is unusually divided and seemingly incapable of selecting even an interim Queen. (The fact that there is no provision for any kind of Queen Regent exacerbates the situation.)
This is indeed the worst time this could have happened: normally the Queen is more ornamental than authoritarian. The High Council does the real work of administering the Queendom. However, with this fractious and divided council, Queen Lilava was a very engaged and directive ruler.
The party begins in the Capital City, Trilivar, as recently "graduated" agents of a mercantile faction that supplies diverse troubleshooting services to public and private factions. In other queendoms, this might be simply called "An Adventurer's Guild"—but in Trilivar, the Mercantile Houses prefer fancier descriptions.
In this backdrop of political confusion and conflict, factions are taking full advantage, crime is running amock, and the very future of the Queendom is at stake. All of that is merely the background for a group of junior "troubleshooters" who are starting out their careers in a troubled, divided land.