Fallout 4: Underground Undercover Fallout 4 Guide

How to unlock: the quest starts when you play The Molecular Level quest while being allied to the Railroad faction (you must have the Boston After Dark quest completed).

Quest objectives:

• Upload encrypted message on any Institute terminal
• Read Patriot's reply
• Meet Patriot
• Follow Liam
• Talk to Liam
• Talk to Desdemona
• Enter report on terminal
• Talk with PAM
• Get password for Code Defender
• Return to Desdemona
• Meet with Z1-14
• Give password to Liam Binet
• Give Z1-14 a day
• Meet with Z1-14
• (Optional) Deposit weapons for rebels
• Kill the tunnel guards
• Return to Z1-14
• Continue working with Father
• Meet with Z1-14
• Warn Desdemona

Contact the Patriot

Scan the network using holotape received from Desdemona

After building the teleport for The Molecular Level quest, Desdemona will give you a holotape while you will be teleporting. Use it immediately after entering the Institute at the terminal before the transmitter. Now you will be tasked with finding the Patriot by following the mission marker. He will tell you about his plan and introduce you to your new helper: Z1-14.

The Patriot - Liam Binet

Go to Desdemona in the Railroad H.Q. after talking with the Patriot (in order to leave the Institute you must complete few steps of the main quest). She will point you to Cambridge Polymer Labs. A quest related to the location will start there - Cambridge Polymer Labs. You can complete or ignore it. Walk to the back of the building where you will find a corridor with many rooms. Go to the first floor.

Obtain the password from the Cambridge laboratory

You should be interested in what is behind the door in the western direction. You can open it using the lock picking (expert lock) or you can walk through the door on the opposite side where there is entrance to the ventilation shaft through which you can get behind the closed door. If you are opening it with the lockpick, watch out for the trap behind it. Leave the building through the same road. Go back to Desdemona.

Z1-14

You can return to the Institute after a short conversation. Meet again with Patriot and give him the password you reclaimed. Talk to Z1-14. He will want you to wait one day so that he can prepare - simply sit on the bench nearby and wait 24 hours.

Optional - deliver the weapon to the rebels

Throw the weapon to the chest in order to make the final part of the quest easier

Talk with Z1-14 again. If you want, you can decide to equip the escaping ones with weapon (optional objective). To complete this part of the quest, you must place 10 weapons of any type in the chest (it is best to search for or buy institute pistols - few of them can be found in the shooting room). You don't need to do it immediately, the rebels will use the weapons much later.

Free the rebels

Kill all the marked synths, you can also lit the gasoline on the ground

Now go to the pointed location where you will find few synth-guards whom you must kill despite the fact that they aren't hostile towards you. The rebels will help you with this objective - you don't need to worry about them, they won't die. After destroying the targets, go back to Z1-14. The quest will be temporarily halted. In the meantime you can go to Railroad H.Q. and complete the Operation Ticonderoga quest.

The quest will be resumed after you complete few quests of the main storyline and reach the Powering Up mandatory quest. Once you finish it, The End of the Line quest will start and you will have a chance to go to Railroad H.Q. and warn Desdemona about the incoming Brotherhood of Steel's attack.

Quest rewards: Experience points, unique Railway Rifle