11 Plot Hooks for the Underdark (DnD 5e)

Do you want your next adventure to take place in a system of spooky caves with glowy mushrooms and color-tinted races that are impossible to pronounce (Svirfneblin, Duergar, and Drow). Well then it sounds like you’re going to be needing a few plot hooks for the Underdark!

In today’s article, I’ll be going over 11 plot hooks for D&D campaigns taking place in the Underdark:

• Outpost Rescue
• Sunlight Stopping Device
• Brain Puppy Tracker
• Follow the Rocks
• Pilgrimage to Lolth’s Temple
• Start at the End
• The Dealings of Duergar
• Spreading Blight
• Down Unda’ Dungeoneers
• La Belle Fleur Sauvage
• A Translator’s Treasure

1. Outpost Rescue

A person of great importance has been captured by a group of Drow who control a small outpost in the Underdark. The local city’s mayor has received a list of demands from the Drow that must be met in order for the hostage to be released unharmed. The players have 24 hours to formulate a plan and try to save the hostage. The party may try to negotiate with the Drow, stealthily rescue the hostage, or even just charge in head-first and break them out by force.

Questions to Consider:

• Who is the important person?
• Why were they captured?
• What are the Drow’s demands?
• What defenses does the Drow Outpost have?

2. Sunlight Stopping Device

Rumors have been spreading of a device in the Underdark that is capable of capturing/stopping light from the sun (maybe it’s just a really really big umbrella). At the moment they are only rumors, but the powers-that-be are worried about a full scale invasion from denizens of the Underdark if they are no longer deterred by the sun. The party is tasked with investigating these rumors and (maybe) figuring out a way to stop any potential Underdark attacks. 

Questions to Consider:

• What is the device and how does it work?
• Who is creating the device?
• What nefarious plans are in store for the device?
• How can the device (or its creators) be stopped?

3. Brain Puppy Tracker

Deep in the Underdark, an ancient and powerful piece of information is waiting to be discovered. It just so happens that the party has been tasked with finding this legendary information. They have been given an intellect devourer, or brain puppy,  who has been specially trained and properly contained. This brain puppy will be able to lead the PCs towards the source of the information, all they have to do is follow its lead and they’ll arrive at the intellectual treasure. Of, and of course somehow not let their brains get psionically eaten in the process. 

Questions to Consider:

• Who is sending the PCs on this quest?
• What is the source of information they are after?
• How is the intellect devourer being contained / satiated?

4. Follow the Rocks

An overexcited miner / businessman has recently discovered an enormous stash / vein / idk of an incredibly rare and valuable mineral. However, the entire area is infested with dangerous plants and creatures of the Underdark. The PCs have been recruited to establish a clear and safe pathway to the underground riches and clear out any creatures that have taken up residency there. They can do this in any manner they see fit, however the miner doesn’t want to see any evidence of violence and they must be able to take a cart (reasonably speaking) towards the stash. 

Questions to Consider:

• What is the mineral, and what makes it so valuable?
• How much (approx.) is the new vein worth to the businessman?
• What sort of creatures live nearby?
• What kind of plants might deter the PCs from achieving their goals?

5. Pilgrimage to Lolth’s Temple

Lolth, the crazy spider queen of the Drow, has numerous temples scattered throughout the underdark and now the PCs have been tasked with making a pilgrimage to one of them. Perhaps to retrieve an artifact or to hunt down some fanatics. Lolth’s followers (and perhaps even Lolth herself if the stakes are high enough) are sure to give them a run for their money as they venture into the sacred grounds. 

Read more about Lolth here!

Questions to Consider:

• Who is sending the PCs to the temple?
• Why are they headed to the temple?
• Is the temple abandoned, or does it get used regularly?
• Is the temple trapped?
• Will Lolth herself intervene to stop the PCs?

6. Start at the End

Imagine the movie The Hangover, except instead of Las Vegas the entire thing takes place in the Underdark. This one works especially well as a one-shot adventure, because otherwise it can be a bit railroady to start. In a night of celebration after completing a massive quest, things start to get a bit fuzzy for the PCs before they black out completely (Tip: use CON Saves to see who stays awake the longest and remembers the most). When the PCs wake up, they are in a wet, dripping cave surrounded by massive glowing mushrooms (aka they’re in the Underdark). They need to find their way out and figure out what happened last night.

(yes it is pretty heavily inspired by the A Night to Remember quest in Skyrim)

Questions to Consider:

• Seriously, what actually happened to the PCs? 
• If the blackout was caused by an individual, what were their motives?
• Do the PCs still have their equipment or do they need to find it?
• How far into the Underdark are they?

7. The Dealings of Duergar

A local merchant, who was otherwise considered to be ‘generally unsuccessful’, has recently started wearing fancy fur coats and flashing expensive jewelry around town. Rumors state that he has struck a deal with some dwarves from the Underdark and they are supplying him with loads of wealth in exchange for… something? The PCs must get to the bottom of these shenanigans and figure out what the Duergar are plotting.

Questions to Consider:

• How is the merchant communicating and interacting with Duergar? (hint they can be invisible)
• What is the merchant providing the Duergar in exchange for the newfound riches?
• Is the merchant working with them willingly, or are they being coerced?
• How likely are the PCs to just kill the merchant and take his stuff?

8. Spreading Blight

Just south of town, a well-known – but seldom travelled – cave ultimately leads to the Underdark. In recent weeks, there have been an increasing number of reports of dead plants and animals in the vicinity of the cave entrance. There is a blight spreading, and it seems to be spreading rapidly. A hefty sum of gold will be awarded to anyone who can 1) determine the cause of the blight, and 2) put an end to it. This plot hook is a great way to kick off a brand new campaign, or to reveal the next large story arc in an ongoing one. 

Questions to Consider:

• Who (or what) is responsible for the blight?
• What will happen if the blight is not contained and fixed?
• Are there any magical effects the PCs will face because of the blight?
• How can the blight be stopped?

9. Down Unda’ Dungeoneers

The PCs have started hearing rumors and seeing posters about a brand new, very exclusive adventurers guild that is holding trials for anyone who seeks to join. Unlike almost every other guild, this one is centrally located in the Underdark. Almost everybody who has attempted the ‘trials’ has failed miserably, and those who have succeeded haven’t been heard from or seen since. Are the PCs tough enough to join the Down Unda’ Dungeoneers and uncover the mystery of the missing adventurers?

Questions to Consider: 

• Is the guild legit, or is it all part of a massive ruse/scheme?
• What do the trials consist of?
• What is happening to the people who succeed at the trials?
• Does everyone have an Australian accent?

10. La Belle Fleur Sauvage

Deep within the Underdark, an exotic and rare flower grows and blooms once every 500 years. A passionate botanist has been studying these flowers their whole life, and has recruited the PCs to go on a quest to the Underdark and retrieve a single petal from a blooming KwestFlower. The botanist knows the location of one of these flowers, as well as the specific time that it should be blossoming. Will the PCs be able to recover this rare specimen without destroying it in the process?

Questions to Consider:

• What makes the flower so special, aside from its infrequent blooming?
• What can the botanist offer the PCs as a reward for the quest?
• Where in the Underdark is the flower located?
• What challenges will the PCs face while trying to retrieve the flower petal?

11. A Translator’s Treasure 

A fanciful gnome by the name of Ranzwick is trying to create a universal translator for helping different races and species communicate. One problem: he doesn’t have enough samples of Undercommon. Ranzwick gives the PCs 5 different enchanted stones (aka recording devices) to collect samples of common expressions in the Underdark. He has requested specific speakers for each of these phrases (one from a Drow, one from a Svirfneblin, one from a mindflayer, etc). Are the PCs up to the task, and if so… how the hell are they going to accomplish this?!

Questions to Consider:

• What phrases should be recorded?
• What creatures must PCs gather the recordings from?
• How viable do you want diplomacy to be?