Below is a GM monologue I gave to players in my Pathfinder 2nd Edition campaign. I have plans to expand this world, potentially with multiple groups of players, with different quests and storylines available to each and with consequences of each group’s actions visible to all groups (a West Marches style, for those familiar with the jargon).
Welcome, Adventurers.
Our setting is the cosmopolitan city of Cork, where mortals of all races and rumor has it sometimes even gods can be found. Beneath the city is the world-famous Dungeon carved out centuries ago by one of the strongest mages ever known, the great wizard Damodred. The Dungeon is not the only structure of its kind in the world, but it is certainly the largest. It has also never been fully explored, let alone conquered.
Every day, adventurers plunge into the depths to hunt monstrous, soulless husks, bringing back their findings for pay, and always looking for a clue to the vaunted Sanctum where the mage’s research — and his accumulated treasure hoard — is presumed to lie.
The Adventurer’s Guild, controlling access to the Dungeon, serves as the de facto government to ensure that some kind of law and order is enforced in Cork. At their direction, newly-arriving Adventurers to join together in Clans, both to serve collective interests and because ‘going solo-diving’ is a common local euphemism for suicide.
The four of you, as well, are Adventurers. You have risen through the beginner ranks of The Winning Hand Clan, and are about to be assigned a Hand, a team for future adventuring purposes. Assignments are random, according to tradition set down by the clan’s founder, but the four of you have met before.
Newcomers to the Clan work in rotating groups, training and drilling their chosen methods of combat, but are never permitted beyond the first subfloor of the Dungeon. As such, you have worked together in the past and know each other vaguely, by name and sight like distant coworkers, and you’ve gotten along fine.
It is now time for your River, a sample mission given to a potential Hand to see if you work well enough together to do so permanently. In this case, the Clan has found a small abandoned keep nearby was taken over by undead, and your mission is to clear it out and figure out why and how they did so. Succeed, and you will have proved yourselves a Winning Hand and be given permission to Dungeon-dive in earnest.
Good luck.