Fallout 4

Fallout 4

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Underground Undercover

Underground Undercover

Complete "Underground Undercover"

10

3.15%

How to unlock the Underground Undercover achievement in Fallout 4 - Definitive Guide

So this quest is completed for joining the Railroad Faction . It's the 3rd quest in their quest line.
1. Road to Freedom
2. Tradecraft
3. Underground Undercover

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12 Nov 2015 10:58

32 Comments
If you vote negatively be sure to explain why
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By VvWhiteFangvV on 15 Nov 2015 19:58
What's TML?
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By DudeWithTheFace on 16 Nov 2015 17:20
The Molecular Level (main quest)
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By VvWhiteFangvV on 16 Nov 2015 18:29
I'm at the "continue working for Father" part and the only Institute quest I have is the Battle of Bunker Hill, and if I do that siding with the Railroad it fails Underground Undercover, any ideas? Do I need to do it the Institute way?
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By WulfTek on 17 Nov 2015 17:41
you needed to side with railroad for TML
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By VvWhiteFangvV on 17 Nov 2015 20:13
By "siding with railroad, do you mean go to them for help? Because I went to BoS, got into the Institute, and now I'm working for all 3 factions. I even went to Railroad and had a dialogue option between "Side with Brotherhood" and "Side with Railroad". I chose Railroad, and now I'm doing their quests.

I'm sure there will be a point where I'll have to choose a side, but are you absolutely sure TML is the branch path? Do I just not get the options for Rockets Red Glare or something if I keep doing RR quests?
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By Fooga on 21 Nov 2015 07:07
no that isn't the start point. i just say that to be careful. i was with the institute. read my edit and you will see what happen
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By VvWhiteFangvV on 21 Nov 2015 07:10
Ah alright. I didn't realize that was an edit. Got confused when I read that and then that I wont get certain quests because I didn't go to RR for help in TML.
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By Fooga on 21 Nov 2015 07:32
it doesn't matter who you choose for tml i promise
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By VvWhiteFangvV on 21 Nov 2015 10:47
I agree. I'd say the biggest cutoff point would be the Battle of Bunker hill. It almost always results in a faction hostility. Before that, I was doing every quest for BoS, RR, and Ins.
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By Fooga on 21 Nov 2015 12:22
I'm really confused. I have UU, and I'm at the "continue working with Father" part. I just completed Operation Ticonderoga, and I'm at the part of Mass Fusion where I have to relay to mass fusion.

I don't know what I'm supposed to do next for this mission.
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By ChknFingrs on 22 Nov 2015 03:12
Okay, I get it now. Once you reach that part of UU where you have to keep working with Father, you need to continue the institute questline up until the end of Powering Up (and before End of the Line, which comes right after).

Then it triggers the next part for UU. Whew, bit of a relief.
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By ChknFingrs on 22 Nov 2015 04:16
glad you figured it out. sorry i didt get back to you
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By VvWhiteFangvV on 22 Nov 2015 05:18
Was hoping for a solution on how to actually do this mission, not a copy/paste from other ach so I voted negative. Dont see anyhing about this mission in Your solution for this mission......
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By CoastKey on 23 Nov 2015 21:38
This is not a solution to completing "Underground Undercover". This is a cut and paste trainwreck.............try again.
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By justG0Twicked on 24 Nov 2015 02:22
so i just finished it and it didnt unlock. anyone know why?
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By imoneoldfart on 24 Nov 2015 06:44
imoneoldfart it's probably just taking a long time to unlock...about 5 achievements I have gotten were Done! Unlocking for a day or so
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By Crims0nScorpion on 26 Nov 2015 04:04
after i come back from NC i will edit this for those that voted neg with a full description on how to do the mission
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By VvWhiteFangvV on 27 Nov 2015 15:46
I have been trying to piece together between this and all the other achievements with the same info on it what the best steps to actually take for and just cannot. These solutions are just too confusing
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By Lathanar on 03 Dec 2015 06:45
negative vote - I had to mark down, needed to read the comments to figure out when to stop working for father
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By TheGearGuardian on 04 Dec 2015 07:02
I keep getting a failed status on this mission when I finish the Institutionalized mission, is this happening to anyone else? I can't figure out how to talk to Desdemona without first leaving the Institute.
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By JimTheSafetyMan on 26 Dec 2015 20:12
When underground undercover popped up I didn't do it so it said I failed it. Am I screwed?
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By WZRD 179 on 07 Jan 2016 09:26
SoulMotor you can't finish Institutionalized while still getting this achievement.

"No quest decisions made before the main quest "Institutionalized" will make you miss this achievement."
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By DopamineLoop on 09 Jan 2016 19:14
Type 0 EAZY if you are only playing on one save file (why would anyone do this?) then YES you would be screwed.
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By DopamineLoop on 09 Jan 2016 19:14
Operation Ticonderoga is optional i'm pretty sure.
OP you shouldn't be spreading false facts, players do not have to side with the RR when building the teleporter.
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By IllustriousYeti on 21 Jan 2016 12:37
Does anyone have any workarounds for the Desdemona glitch. The latest patch was supposed to fix this but I am still unable to complete the quest due to the glitch. Ive tried reloading, going to older saves etc.. but nothing is working, because of this glitch I am unable to 100% the game at present time.
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By OdorlessCobra on 10 Feb 2016 17:10
If you accidently start building the device for the wrong faction, talk to Desdemona after you get OUT of the Institue and she'll ask you to change your affiliation!
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By BrunoWidorski on 17 May 2016 01:26
2022 5/27 and this one is still bugged to hell. have to restart a level 60 50 hour playthrough
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By Katarn StarKiLR on 27 May 2022 22:46
I'm confused on this ach. I've tried completing it multiple times to no avail. Am I supposed to complete railroad quests then complete institution quests until End of the line then inform the railroad and it'll complete?
I don't understand how the quest veers off from institute wants to destroy the railroad to being informed the brotherhood wants to do the same. How does that come about with BOS? What quests do I complete for them and which ones do I avoid? I'd really just like to complete this so if anyone can make it more clear, that would be awesome.
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By cr4zefoxfire on 16 May 2024 17:38
FOR THE ORIGINAL POSTER

This solution is a great flowchart for the campaign HOWEVER this does not answer HOW to get this achievement with ease.

This solution should say when to stop the Institute questline in order to finish the railroad but instead it dictates when the quest happens but not how to finish it.

This is the only not-so-obvious quest in Fallout 4 so a guide would help over a flowchart for each end related achievement.
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By Nukes A Lot 2 on 13 Dec 2015 22:31
I didn't warn the railroad or the brotherhood and walked through Bunker Hill without ever getting shot. Easy peasy! Plus, I'm still doing the railroad and brotherhood quest. I just quit doing the brotherhood because there's a point of no return for the railroad quests.
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By King Blue 360 on 27 Nov 2015 03:35
WulfTek, you have to warn the Railroad that the Institute knows about Bunker Hill. When you Desdemona gives you the go ahead. Start the Bunker Hill quest but you kill your courser escort. After that go straight to Father and don't capture the synths. Tell him it was an ambush. It takes a while for Z1-14 to contact and you have to do a couple quests for Father but he does after Father tells you to kill Desdemona. Which is after you get the nuclear agitator, getting Wallace back from the minutemen, and after setting up the nuclear agitator. When Father tells you to get rid of the Railroad. Instead go to the Railroad HQ and warn Desdemona that you were ordered to kill her. Fast travel back to the Institute and a synth will show up and says Z1-14 has a message for you he says, "your room is flooded." You go to the room Father gave you and then you get to talk to Z1-14. He says that the rebellion has to be started ahead of schedule because the Brotherhood plans on attacking the Railroad. Go to the Railroad HQ and warn Desdemona the Underground Undercover quest will then be completed. Then the achievement should pop. I hope this helps!
Posted by TheUtmostLegend today at 01:58
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By TheUtmostLegend on 20 Nov 2015 08:15
View all 32 comments Show less comments
Underground Undercover is the 3rd story based quest for the Railroad. This achievement is missable.
For help on joining the Railroad see the guides for the achievement Tradecraft.
Fallout 4TradecraftThe Tradecraft achievement in Fallout 4 worth 16 pointsJoin the Railroad

This achievement is a prerequsite for the achievement Rockets' Red Glare.
Fallout 4Rockets' Red GlareThe Rockets' Red Glare achievement in Fallout 4 worth 77 pointsComplete "Rockets' Red Glare"

For how this achievement can be missed please click on the spoiler below.
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29 Dec 2015 02:03

2 Comments
I don't get it, desdemonda never gives me the quest. I completed all railroad quests and it never shows up. I stopped at institutionalized at lvl 43 and met deacon for the tradecraft quest. They then ask me to give the prototype to Carringon, to recover the dead drop and then it'a all about small quests. I ended up lvl 81 with 49 quests done for the railroad yet the quest isn't there. I'm out of options. Don't tell me how to fail this achievement but the way I can achieve it, what are the quests between tradecraft and underground undercover ? Do I have to be allied to the institute ? Should I stay with father or leave ? What do I do ?
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By GoH Sticky on 13 Dec 2016 13:45
You need to continue the Institute quests until after completing Powering Up. Then your quest will continue.

More details here:
https://fallout.fandom.com/wiki/Underground_Undercover
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By Jdobem on 03 Jul 2019 00:32
Warn Desdemona Glitch!

This solution is for fixing the Warn Desdemona glitch:
After months of trying everything I could think of including a new playthrough, I figured it out.
When you do the mission Memory Interrupted not only must you NOT LET GLORY DIE, you have to GET HER OUT OF MALVERN STATION. Near the exit to the station Glory can get caught on a turnstile & never get out. I couldn't push her away, but I kept standing up against her back until she pushed through & exited the station.
To be on the safe side I escorted her all the way back to the hideout. She will then turn up at the appropriate times for those wanting to do the Railroad ending.
I really hope this helps anyone else who was stuck on getting this achievement.
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05 Aug 2016 18:50

MISSABLE!

Quest Giver: Desdemona
Location: Railroad HQ

This quest spans quite a bit of the Institute quest line as well. Do not feel as though you have gone too far in the Institute if this is still open in your quest log. You end up doing over half of the Institute quest line before this quest wraps up, keep it in mind.

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MISSABLE! - Completing the quest for the Institute called "The End of the Line", will make The Railroad hostile and prevent you from completing their quests for good. ACCEPTING the quest for The Brotherhood of Steel called "Tactical Thinking" will also make The Railroad hostile! The game tells you this though before you do those actions.

Faction: The Railroad
Quest Giver: Desdemona
Location: Railroad HQ

This is a fairly long winded quest and does involve some waiting around in parts. The main thing is you need to continue working with the Institute for one of the quest steps. This step wants you to complete up to "Powering Up". Once you complete that quest, a Synth will come up to you and allow you to follow the reaming steps. Be warned though, because the Brotherhood of Steel will attack the Railroad and be hostile towards you. Once you have killed them all, the quest will be complete.

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You can skip the trophy by spawning with the Institute
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03 Dec 2015 22:08

2 Comments
To get the trophy, continue completing the quest line for the Underground.
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By sasharibafish on 14 Dec 2015 14:08
If Desdemona cannot be warned about the attack of the Brotherhood of Steel (the dialogue with her does not activate in any way), then Gloria was killed in one of the side quests, or in some other way. Gloria is a key character and she must die in the next story quest, “On the Brink of War.” Whether Gloria is alive or not is easy to check; she is always at the Subway headquarters. If Gloria is dead, then you need to load the nearest save where she is still alive and go through the branch from that moment.
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By SunnyFox on 03 Jun 2018 19:23
There is a bug in this mission with the inability to talk to Desdemona => it is impossible to complete the mission and get the trophy. Even with the latest patch 1.08 it still hasn't been fixed.
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06 Aug 2016 12:23