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Fallout 4

Underground Undercover

Nathan Garvin
Important Items in This Area
Massachusetts Surgical Journal

Underground Undercover (Part 1)

Now that you have a means of coming and going to and from the Institute as you please, it’s time to start working at completing the Railroad’s schemes. You should have used the “Network Scanner” holotape on the console just outside of the relay to contact Patriot, in which case you would have been told to meet it in the Advanced Systems maintenance room. From the doors leading to Advanced Systems head north, north-east and follow a blue line down a ramp. Head past a stairwell and go through some Sliding Doors to the north, then east, then south to find the storage closet where Patriot awaits. Be sure to equip your "Charisma" iconCharisma gear ahead of time as you can get a speech check here). He’ll be very surprised to see you. Talk to him about the Railroad for awhile and he’ll soon lead you to a Synth that is waiting for freedom itself, Z1-14. You can get a moderate speech check here so go for it if you can and go talk to Liam. Before you go through with your plan though, Liam will say that he needs a password and to find it, you’ll need to get back in contact with the Railroad.

Fast-travel back to "Railroad HQ" iconRailroad HQ (yes, you can teleport right from the Institute to the Railroad HQ, which seems a little… risky?) and once you’re back the team members will undoubtedly marvel that you made it back in one piece. Talk to Dez next to tell her what happened and she’ll ask you to type up the report on PAM’s terminal so the machine can analyze it for her. Activate the “PAM Mainframe Terminal” and select the entry “[Enter Institute Report]”, afterwards talk to PAM and she will do the heavy-lifting and narrow down logically where the password Liam needs likely is. She will direct you to head to “"Cambridge Polymer Labs" iconCambridge Polymer Labs”, which is west of the "C.I.T. Ruins" iconC.I.T. Ruins.

Cambridge Polymer Lab

Fast-travel to the Cambridge Polymer Lab (or nearby, if you don’t have the map marker) then head inside the building. As soon as you enter this place, you will talk to a robot named Molly, who is quite keen on recruiting you as an employee. Go ahead and play along here, but equip your Charisma gear before you begin the interview (there is a speech check to pass). Once you do get to the interview part (which consists of a single question), your answer dictates what job you will get. You can of course pick whatever you want, but only the easy speech check gives you XP (the position of sales coordinator). You will then be asked if you want to attend the employee orientation or not. It is honestly a waste of time, but you can choose to follow Molly to a destroyed viewing area to learn about Cambridge Polymer Labs.

After the orientation, follow Molly into the Clean Room and loot whatever you wish before heading in (save the upstairs part for now). You will also get some crappy clothes depending on your job here (which aren’t worth anything). As soon as you enter the clean room, Molly will announce that overtime is mandatory and lock you inside. Gah! Leave the room through the nearby hole in the wall as radiation is blasted into the room.

Well, the quest has started in earnest and you are told to “Complete the Research Project” (or find another way to escape). It is in your best interest to complete the project however, so that’s what you’ll do. Head into the first room here (which is the “Experiment Room”) and read “Ericka’s Terminal” to get a glimpse of what happened here. The work area is just to the east, which you should get familiar with as this is where you’ll do the actual experiment at.

A quick note about this work area: to the left are two slots where you put the agents and to the right is where you put the isotope. You can read the terminal here to learn that the two agents that you need are “Gold” and “Lithium Hydride”, so you will need to find those and the isotope to complete the research project. They give you the “Unidentified Agent 11317 right at the start. Go ahead and pick it up, then put it in the agent container. Use the terminal now and scan it to learn that it is Hydrochloric Acid. Not what you need, but you know how to scan things now. Put it back in your inventory to make room.

OK, time to explore this facility. Out in the lobby area you will undoubtedly find some Ghouls. Kill them as they are getting up and even more will come (some from upstairs), so take them down. Go explore the south-west room now to kill a Ghoul and find a Hazmat Suit and “Unidentified Sample 3111” on the shelves. From there, go up a room to the west room for two more Ghouls and “Unidentified Sample 413” on the table by the window. This room leads north into another room that holds “Unidentified Agent 65” and the all-important “Isotope Containment Terminal”. You need this, so hack the terminal [Novice] and open the door. Doing this will set off an alarm and cause a Glowing One to rise up from the waste. You can get to the isotope area by taking the north-east room on the lower level, but before you do, pop some "Rad-X" iconRad-X or put on the Hazmat Suit you found as the room is highly radioactive. Head on in there though and kill the Glowing One. Once you kill it, check the corner of the room (on the shelves) to find a vial in a holder. Pick this up for “U-238”, the isotope you need.

You have to explore the top floor now, which will be fun. Head up there and head into a room to the east. In the closet in here is a Ghoul you can kill. Check the deck in this room (by the ramp) to find a skeleton with “Unidentified Sample 49” on the desk. There is also a “Suicide Note” on the desk (very sad). Loot the room now and head up the ramp. Avoid the holes in the floor as you head north, then another as you turn west, but drop down a third hole at the end of the southern passage, then kill the Ghouls in the room you land in. Once done, check to the right of the terminal for “Unidentified Sample 611”. The desk in the middle also has the “Radioactive Containment Password” (not that you need it). Be sure to use “Bergman’s Terminal” near the “Unidentified Sample 611”, which you can use to select the option “[Password Request (Archive)]”, which gets you the password you need for the quest “"Underground Undercover" iconUnderground Undercover”. You can also select the option “[- Facility Defense Systems -]” which will let you override Security. This is part of the optional objective to find another way to leave the lab. As usual, you can do as you wish, but since you’ve come this far, you might as well just complete the experiment. If you do want to do this though, simply leave through the clean room and Molly will be hostile. You will have to take her out. Follow the rest of the guide though (either way) to get all the goodies out of this place.

Time to get out now! Head to the door and disarm the Laser Tripwire by the door. Open the door with the terminal. Note that outside this door, you can turn around and hack the terminal [Expert] if you want the XP. Jump the gap and explore the upper left portion now to find a safe [Expert] and other goodies. Head back to the experiment room now as you have everything you need. The first step here is to identify all of the Unidentified Samples you have. Put them two at a time in the containers on the left and use the terminal to scan them. Here is the list:

Unidentified Sample Scan Result
611 Gold
65 Tungsten
3111 Lithium Hydride
413 Gallium
49 Cobalt

Knowing this, put the Lithium Hydride into the left slot on the left, Gold on the right slot on the left, and the U-238 into the Isotope Slot. Use the terminal now and run the test, then exit the terminal and watch what happens. Once it is done, head to the left receptacle for the “Piezonucleic Power Armor Chest”, which is… quite nice. You have now completed the experiment.

Head back to Molly now and tell her that you are done. She will lift the lockdown and will lead you to the director. Go ahead and follow her as she takes you upstairs. Stay with her and she’ll open up the Director’s Office who is a Feral Ghoul. Because of course he is. She will remind him of company policy though and pay you for your effort (25 Pre-War Money) and then shut down as there is no more work to do and they need to have some drawbacks. Ha. Be sure to loot her for the “CPL Director’s Key”. The quest will officially be done at this time.

Objective Reward
For completing the research project 236 XP

Before we let you go though, you have looting to do! This director’s office has a "Fusion Core" iconFusion Core in one of the corners and more importantly the “Massachusetts Surgical Journal” on the director’s desk. You can also check out his terminal to see his final messages and what he was dealing with at the time - still, locking people in was plain evil. You can now loot the office area up here and an area by the stairs that has a ton of cabinets in it. Now you are done with this area.

Underground Undercover (Part 2)

So, you should have the password now, correct? Good, go ahead and head back to the Railroad HQ at this point to talk to Dez like the game wants you to. Dez actually has much bigger plans than Liam does - she wants to free all of the Synths at the Institute. Go big or go home, right? Ambitious, but you will have to head back to the Institute and talk to Z1-14 and Liam first. Go ahead and fast travel-there now.

Go find and talk to Z1-14 about the new plan. Encourage him and he will ask for a day to put his plans in place, suggesting that you will likely have to fight Synths to do this but many may join in once they rise up. You will have to “give him a day” at this point. Save and make sure your

Charisma gear is on, then go talk to Liam. Give the password to him and then you can try to pass a moderate speech check about his feelings on “violence” (hint: he is not a fan). From here you need to wait a day, which is simple enough to go find a chair and wait for 24 hours. Go ahead and do that now.

Once the day is passed, go talk to Z1-14 again and he will tell you that the plan is in place. However, you need weapons. You can actually get an optional objective to give them weapons if you tell him you have weapons (which includes placing weapons of yours into a crate), but who wants to find and give up weapons? Thankfully, Z1-14 has another plan in place and asks if you can kill some guards. No problem here! The plan is to take out the guards who are supervising the expansion team to give his fellow Synths time to stage a construction collapse and build weapons themselves. Hehe…

Institute Sublevel 21-D

From the door leading to the Robotics area head west, south-west down a ramp (follow the red line) then go south through some Sliding Doors past some stairs. Turn east and go through another Sliding Door to reach an elevator, which will take you down to the newly excavated area, where you’ll find the Synths loyal to Z1-14 being guarded by some levelled Guard Synths. To start off with, be aware that you don’t have to worry about the AI Synth allies dying. They will just fall down hurt like a companion would, so don’t worry about collateral damage as much. Try to hide and get a sneak attack in on a guard and the battle will begin. Focus on a group of two first as the workers will engage the other enemies which will help you a ton as you do not want them all on you. Knowing that, take down the group you first target, and then focus on helping the AI one guard at a time until you take them all out. The shift leader will thank you and tell you to go.

Return and talk to Z1-14 now and he’ll report no alarms. Excellent. For now though, before you continue he urges you to “Continue working with Father” and puts this quest on ice until later on. You should have completed “"Institutionalized" iconInstitutionalized” earlier, meaning your next quest for Father should be “"Synth Retention" iconSynth Retention”.

You can also blow your cover by turning on the Institute and killing people (Father makes a fine target, but anybody will do the trick). Once they’re hostile the quests “Banished From the Institute” will start along with “"Burning Cover" iconBurning Cover”. Merely escape "The Institute" iconThe Institute using the relay to complete “Banished From the Institute”. Once you’re out return to Desdemona at the Railroad HQ, who will be disappointed, but won’t hang too much blame on your shoulders. At this point, she’ll suggest you use the Minutemen to fight the Institute, and essentially you’ll need to complete the game with the Minutemen (starting with the quest “"Form Ranks" iconForm Ranks”), whose army can be used to liberate the Synths by force. Of course, this won’t let you complete the quests “Underground Undercover” or “"Rockets' Red Glare" iconRockets’ Red Glare”, amongst others, so it should be considered sub-optimal. Yeah… that’s right, the Minutemen questline is pretty much the “Plan B” questline, for if you mess up with another faction. Lame.

Objective Reward
For escaping from the Institute 407 XP
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Guide Information
  • Publisher
    Bethesda Softworks
  • Platforms,
    PC, PS4, XB One
  • Genre
  • Guide Release
    16 December 2015
  • Last Updated
    11 May 2024
    Version History
  • Guide Author
    Nathan Garvin, Greg Wright

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