Well, this reminds me a bit of
Dungeon Keeper... one of the first obstacles to deal with is the fact that by the nature of them residing in the dungeon, the PCs have a more passive role than is traditional. I'd encourage them to go a-raiding and ker-pillaging, using the dungeon as their base of operations. It'd be easy enough to have them as lackeys that work for the Big Bad in charge of the dungeon, so you've got a built-in NPC contact for them right there.
It would be helpful to know what level/races/classes the PCs are; something appropriate for low-level characters is inappropriate for high-level ones, and vice-versa. The more info you provide us, the better we will be able to assist you in picking or designing a module.
-----------------------------------------------------------------------------------
Now, if you mean "runs the dungeon" as in "participates in clearing the dungeon and defeating its inhabitants", that's a different story. It seems a bit odd that the party would be part of a larger group in this case, unless there's ye olde torches-and-pitchforks mob heading in there. Of course, that'd be a recipe for disaster, given how commoners don't even stand up well to housecats (let alone orcs or other things suitable for PCs to fight).
Off the top of my head,
A Dark and Stormy Knight would be suitable for a 1st-level party. Of course, without knowing what level your players are, I can't suggest anything higher than that.
After all, the Tomb of Horrors is probably not what you're looking for.