Baldur's Gate 3: Aid The Underduke Walkthrough

This guide details how to complete 'Aid the Underduke' in Baldur's Gate 3, covering the journey from the Guildhall, Counting House, and Sewers.

RPGs are notorious for lengthy quests filled with many possible outcomes. Some of these will affect many different choices you can make down the line, and some can even affect which ending you may get in a game.

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Baldur’s Gate 3 is filled to the brim with such quests. This quest will not only decide a companion that can join your party but also decide if one will leave it. Not only that, it will shape events that will affect the final battle of the game.

Before starting this quest, be sure to have recruited Jaheria. Head on over to the coordinates of X: 5 Y: 75 in the Wyrm’s Crossing location. There will be a building on your map named “Sharess’ Caress.” Walking inside will display its name on the screen. Follow the red carpet all the way to some stairs. Just before the stairs will be some NPCs sitting at a table. Talk to the one named Earspoon.

Depending on your choice, the information you receive can vary. Regardless, your journal will be updated, and you will now have the quest in our journal. Your next destination is Heapside Strand. There is a waypoint near this location — you should be trying to activate each one of these waypoints whenever you come by one, as it will make fast traveling around the many locations featured in the game a lot easier.

Head northeast from the waypoint and take the second left turn you see. This will have you cross paths with the NPC known as Tusgront at X: 55 Y: -105. Navigate the dialog choices and then make your way through the door to the left of Tusgront. You will now be in the Guildhall location. Make your way through the area to the coordinates of X: -35 Y: 775. This will put you in “Guildhall - Nine-Finger’s Office” where you can find the NPC Nine-Fingers Keene. Let Jaheira do the talking when the dialog option appears.

Once the dialog has concluded, you will need to make your way to Tut Thistlebog. You can find Tut over at X: -15 Y: 740. This interaction will give you the information you need regarding the Stone Lord and the Counting House.

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Thanks to your last conversation, your journal will now have a new objective to pursue. Head back out the doors you entered the Guildhall and head on over to X: 95 Y: 145. You will be standing on a bridge that leads to two large doors with guards stationed in front of it. These guards will not stop you or hinder your passage; you can freely just walk on past them into the building where many other patrons will be scattered about. Speak with the NPC named Head Clerk Meadhoney. You can find him standing behind the counter. This will get you the Bank Pass.

To the left of Head Clerk Meadhoney, you will see a large gated door and some guards outside it. Speak with them and show them the Bank Pass when they ask for a Vault pass. Head all the way down the stairs and interact with the Double Doors. Go through them and make a right turn. More guards will ask to see your pass. Show it to them and head through the open doorway they are standing in front of. Head to the end of the hallway, and you will come to a large vault door. Interact with it to gain access to “The Counting House - Vaults.” Opposite where you entered will be some doors; open and head through them. Head all the way down the hall to X: -950 Y: 780.

Here, you will need to input a specific set of numbers to have the vault open for you. If you stand in front of the plaque, there will be 9 squares in front of your characters. Separate one of them and have that character walk onto the top left square, then the top right square, then the center square, and finally the far right square. If that sounds a little confusing, imagine it as looking at a keypad with 1,2, and 3 on the side where the vault door is. The code would be 1-3-5-6.

This will cause the vault to open up. You can now reunite your party and head through the vault door. On the other side, there will be some large doors. Moving your mouse over here will show that you will leave the area, this will take to you the High-Security Vaults location. Before doing so, be sure to rest up and make any preparations you need before combat.

Once you arrive in the High-Security Vaults, you will enter a cutscene. This involves a less-than-happy reunion between Minsc and Jaheira, followed by a combat encounter. You will have the high ground; use that to your advantage for as long as you can. Once all your foes have been felled, head on over to the largest vault doors yet. These can be found over at X: -695 Y: 875. Inside, you will be able to update your journal.

Travel back to the Lower City and to X: -160 Y: -60. Here you will find a manhole cover into the sewers. This sewer system can be pretty labyrinthine, and it is easy to make a wrong turn. There are plenty of enemies in here as well, so it might be a good idea to make a save before heading deeper into the sewers. You do not have to worry about getting lost or spending an hour retracing your steps after exploring every nook and cranny. This is thanks to the coordinates displayed at the bottom of your minimap. You can easily navigate to your destination by just heading towards the following, X: -165 Y: 880.

This will put you in the Abandoned Cistern. Have your frontliners Jump up onto the pipe with your back row character safely behind them. Follow the pipe in a westward direction. This will trigger an NPC and result in a combat encounter. Your Backrow can safely deal long-range damage as your frontliners charge in to make short work of the enemies.

Once the enemies are dispatched, if you turn to the left at the end of the pipes, you will come to a large pump machine. This will be located at X: -205, Y: 875. This pump is the next puzzle you will need to tackle during this quest, but it is a rather simple one. You just need to interact with the Water Level Valve and watch the top of the screen.

You will see “Water Level Rising,” “Low Water Level,” and “Perfect Water Level.” Once it hits the Perfect Water Level, turn the valve again. Afterward, turn the wheel called “Temperature Valve.” Again, you will see several names coming up at the top of the screen. You want to hit “Perfect Warmth” and then interact with the wheel again.

Go around the corner and over the wooden bridge. You will see that directly under this wooden bridge is an access tunnel that is now wide open. Continue down the wooden path and down the slope to the open hatch and head on through this hatch.

If you need to recover after that last fight, now is the time to take a short or long rest. Make your way down the tunnel; it is a straight path with no deviations. If you want Minsc to join your party, you will need to be sure to not kill him. You can do this by using the Non-Lethal toggle. You can find this toggle In the Passives tab next to Items. Check through the bodies of all your fallen enemies. On one of them, you will find a note called “Letter from Orin.” You will need to read this note in order to update your journal.

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You can now make your way out of the sewer and back to the Guildhall. The next part of this quest involves combat. So once again, take a short or long rest and make sure all your characters are in peak condition. Speak to Roah Moonglow, and she will desire to overthrow Nine-Fingers. You have the choice to side with Roah or not. This will determine the side you fight you.Who you side with will determine who you speak with after the combat is over. Speaking to the leader of the guild will be the final step to complete this quest.

In both cases, whoever is in charge will aid you in the final battle. So your choice really comes down to what you feel is right and whose side you want to be on. If you side with Roah, she will give you a reward. It’s nothing great and should not sway your choice. You are able to kill both leaders, but by doing so, you will have nobody to aid you in the final battle. This makes killing both leaders the worst outcome. Siding with Nine-Fingers means you can take the 10,000 gold from Roah’s corpse. This is the gold that she stole, and you can use it to easily resolve an entirely different quest.

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Chad Thesen is a passionate fan of anime, video games, series and films (Both animated and live action). Many years of experience has left them with a developed and deep knowledge of the intricacies and nuances of these mediums. He loves discussing his observations of games and of shows with others who share these interests. He is up-to-date on the latest news and trends in the industry and is also skilled at analysing and critiquing these mediums to provide thoughtful insight.