Looking for Underdark Inspiration (help me flesh out an adventure)

[Mercurius]

I need to plan an adventure for a party of six 8th-level PCs tonight and have been super busy, unable to flesh out details.

The Hook (What the PCs know)
*Their home city has been undergoing invasions "from below" - previously unknown pale dwarves bursting up through cellars and sewers and stealing people.

*The PCs have run into these guys a few sessions back when they saved one of their companions from being sold to them by gnolls; the dwarves used explosives to cover their tracks as they fled into caves.

*The lords of the city have offered to pay for information as to what is going on, why the dwarves are attacking, who they are, etc.

*A craftsman has asked them to find his daughter, who was taken by the dwarves through his cellar.

The Background (what the PCs don't know)
*Under the city is a vast dungeon complex similar to Waterdeep's Undermountain - this is well-known and a common locale for adventuring. What is not well-known is that it connects with the vast Underdark domain, which has had very little contact with the World Above, at least in recent known history (most of history beyond a couple hundred years is lost to humans for reasons I won't get into now).

*The pale dwarves (duergar) are essentially Underdark mercenaries stealing humanoids to sell to this world's version of the drow, who in turn are transforming them into drider in order to build an army.

*The drow themselves are undergoing a schism - the majority who want to invade the World Above and seek revenge upon their kin, and the minority who wish to find their own way, even establish peaceful communication with other peoples.

*The drow in turn are being manipulated by illithids, who are the agents of the aboleth, who serve their dark master from the Far Realm who seeks entrance into the world in order to, I dunno, eat it.

The Adventure (What I don't know - yet)
*Presumably the PCs would go through the craftsman's cellar and track the girl. Unfortunately they don't have a ranger or trained tracker, but I have a stash of magic items that they retrieved on their last adventure which I haven't detailed yet, so I was thinking of making one of them a "tracking device."

*The first adventure should be relatively straight forward: find the girl/save the girl, but how to flesh it out? I want this to be the prelude to a possible Underdark campaign...or not, depending upon what the PCs decide to do afterward. They've already agreed to help the craftsman find his daughter, but after that they may follow some other lead - last session I gave them a bunch of adventure hooks and they chose this to start with, but could very well go down another after saving the girl.

In short, I want to develop a short adventure (one or two sessions) that gets them a nice taste of what the Underdark has to offer. One idea I had was that when they find the girl they also release other captives of the duergar, one of whom is one of the "good" (unaligned, really) drow, who would be an NPC contact going forward and might give them a better idea as to what is going on.

What I want to avoid is "You go down a long passage for what seems like miles, and then fight a weird creature, then go down another passage for miles, and fight an even weirder creature." Some of that is fine, but I'm looking for ways to break it up, flesh it out, diversify their experience. Skill challenges, role-playing opportunities, strange underground locations, etc.

The floor is yours.

 

[Traveon Wyvernspur]

For me, the Underdark is a very fun and compelling place to adventure. You could easily have a whole campaign down there and not get bored if the storyline is strong enough.

A couple of ideas for your adventurerers:
1) Have them go down one of the tunnels and find some Drow experimenting on captured slaves making them into driders and other monstrosities.
2) Perhaps have them run into one of the mind flayers and a few of its minions and if they can beat them uncover some clues to whats happening, maybe a missive of some sort.
3) Have them run into the neutral aligned Drow in some hidden side tunnel and almost get into a fight with them, then they can figure out these aren't the bad guys, but are some who want peace and will give them some more information as to what's going on down there.
4) I've always been a fan of (if one of the members is a priest, paladin, ranger, or druid) having their diety come to them in a dream and setting forth a quest of some sort that would have them try to find the mind flayer hive and destroy it so that the BBEG won't cross over into their realm and eat it.

Just a few ideas, maybe you like em maybe you don't

 

[Mercurius]

Thanks for the ideas - good stuff. I've actually already used your first idea in a mini-adventure I ran them through a few months ago with different characters, most of whom died. But they found a drider hive, which was sort of reminiscent of the Aliens movie, including one of their companions who was halfway transformed. But I wanted to give them a taste of the drow and the Underdark with characters that they weren't as attached to so that when the larger campaign arc started they (as players) would be a bit more careful and have a (healthy) fear of the Underdark.

The neutral drow are going to be a major plot arc that I want to exploit. It definitely makes the whole Underdark thing more complex, not just "kill the evil X." The trick will be introducing them in such a fashion that it is a surprise when the PCs realize they are not inherently evil.

I canceled the game session tonight so I have a couple more weeks to think about this.

 

[Gilladian]

I'd think the first thing they would find as they went after the girl would be some sort of "outpost" the duergar are using. There could be a barracks, holding cells, a few rooms for the leaders of the raiding parties, etc...

Further "back" in the tunnels, you could have a duergar village-equivalent, set up on a trade route where slave-buyers come to purchase new captives. Here you could have a slave-market, an inn or two, a pace for caravans, and larger slave-holding facilities. There might even be a temple, "farms" or the underdark equivalent, etc...

 

[Herobizkit]

IMO, the first thing you need to do is to make the evil Drow less "evil Elf" and more "evil Fey". They should be an unworldly, eerie experience that should put them on edge. Don't just place them as enemies to fight - get in the PCs heads and make them squirm.

If you really wanna mess with 'em, make the race insubstantial/incorporeal, or give them the Displacement quality. Or, even better, give them all the Shadowdancer "shadow step" ability and combine with "Invisible in Darkness" (and can only be seen in bright light); this puts the PC's between a rock and hard place (fight blind or give the drow the ability to 'teleport' around the battle area).

As for adventures, well, there could be all kinds of weird stuff underground. Exotic places can be just as interesting as monster battles. For example, giant caves filled with glowing quartz crystals (basically a huge geode), magma rivers, caverns completely covered in ice, entire towns of elemental kin (salamanders, mephits)... crazy Underdark druids and their mushroom (or slime) groves (qv the Oozemaster PrC)... and deep gnomes, of course.