Underground Undercover

Underground Undercover is a Railroad main quest and an achievement/trophy .
==Quick walkthrough==
==Detailed walkthrough==
After the Sole Survivor gets into the Institute, the Railroad wants them to make contact with an anonymous person inside, nicknamed Patriot, who has been helping synths escape. Tinker Tom modifies the Network scanner holotape, or provides the encrypted message holotape, in order to be able to upload a message for Patriot to the Institute's network in the hopes that Patriot sees it and comes forward to identify themselves.
After uploading the message, the Sole Survivor should read the 'Urgent Reply' message, which turns out to be a message from Patriot telling the Sole Survivor to meet him in a maintenance closet. Patriot turns out to be Liam Binet, an Institute scientist and son of Alan Binet, the head of the Robotics department. Liam expresses surprise that anyone decoded the messages he was sending out with each synth he freed and were then able to contact him back, and he is excited at the prospect of coordinating with the Railroad.
He introduces the Sole Survivor to a synth named Z1-14 who has been working with him to help synths escape. They discuss how many synths are ready to leave and propose a plan to free all thirteen at once with the Sole Survivor's help. To escape, Liam will need to bypass SRB electronic security to open some doors, but he isn't able to crack it. Instead, he requests a pre-War admin password from the surface. He recommends asking the Railroad for any leads on where to find one. The player must complete the quest Institutionalized at this point in order to be able to leave the Institute compound.
The Sole Survivor returns to Desdemona at Railroad HQ and is instructed to enter their mission report in the terminal in P.A.M.'s office. P.A.M. analyzes the data and recommends that the login credentials for Wilfred Bergman may be found in Cambridge Polymer Labs. Desdemona instructs the Sole Survivor to retrieve it while they consider Liam's plan.
The password can be found in the laboratory section of the building on the second floor. In order to access it, however, the quest Cambridge Polymer Labs must be completed before escape from the building is possible.
Looking over Liam's plan, Desdemona concludes that if it is successful, it may never be possible for Liam to free another synth ever again due to the Institute going on high-alert following such a security breach. She proposes instead that they should use this opportunity to free every synth in the Institute. To do that would require the synths themselves to rise up and fight for their freedom, instead of operating in the shadows. She instructs the Sole Survivor to give Liam the password he requested, but then to cut him loose and coordinate with Z1-14 instead from then on.
Back in the Institute, the Sole Survivor gives Liam the password, then meets with Z1-14 to discuss Desdemona's proposal. He agrees with the plan and asks for 24 hours to ensure that it is possible. He speaks with the other synths and is surprised at how many volunteers he receives. They will need weapons, however, so he requests that the Sole Survivor aid them by killing a few guards so they can stage a construction accident, allowing a few synths to go into hiding in order to construct weapons. The Sole Survivor may optionally offer to provide additional weapons, which Z1-14 instructs to be placed in a maintenance closet.
The guards are in a maintenance tunnel between Synth Retention and Robotics. After they are dispatched, the worker synths will give their thanks and collapse the tunnel after the Sole Survivor departs. Speaking with Z1-14, he gives his thanks as well and states that they need time to prepare. In the meantime, the Sole Survivor should keep working with Father until they are ready. At this point the quest is put on hold until the Institute orders the Sole Survivor to take on the Railroad during End of the Line.
After meeting with the Directorate, a runner will arrive in the meeting room with a message from Z1-14 that the Sole Survivor's quarters have flooded and they are needed there immediately. When they arrive, Z1-14 states that he's discovered that the Brotherhood of Steel has found the Railroad HQ and are preparing to attack, so the Railroad needs to be warned as soon as possible.
==Quest stages==
==Notes==
* The signal interceptor does not need to be built with the Railroad to be able to start this quest. After finishing The Molecular Level, simply talk with Desdemona and accept her offer to work with the Railroad and this quest begins.
* Tinker Tom will provide the encrypted message holotape unless the player character has the network scanner holotape in their possession, in which case he will modify it to provide the means to contact Patriot. If the modified network scanner is subsequently given to another faction (Sturges or Proctor Ingram) before sending the encrypted message, a new objective will appear to return to Tinker Tom to collect the encrypted message holotape.
* Becoming enemies with the Institute fails this quest and any other incomplete Railroad quests, starting the optional Railroad quest, Burning Cover, thus ending the Railroad questline.
* If Tradecraft is not completed before becoming banished from the Institute, this quest does not start at the conclusion of Tradecraft, and is unavailable. Similarly, Burning Cover also does not start and is unavailable.
* At quest stage 500, returning to the Railroad starts a speech from Desdemona where she refers to them as "the Wanderer" instead of their actual, chosen code name.
* As continuing to work with Father means completing Mass Fusion, the Brotherhood of Steel becomes hostile to the Sole Survivor afterwards.
* The optional "deposit weapons" objective is completed when weapons (not counting explosive weapons such as land mines and grenades) have been placed in the marked locker 8-10 times. Placing a stack of weapons is seen by the game as only one weapon, so the player character must put them in the crate one at a time. It is not however, necessary to exit out between each deposit.
** This objective updates even after its completion; removing enough weapons from the locker will unmark it as completed while Underground Undercover is active.
* If all of the guards are not dispatched quickly enough in the tunnels after the Sole Survivor is detected, the Institute may become hostile.
* The final meeting with Z1-14 (after completing Powering Up) causes Operation Ticonderoga to fail. Despite the warning that Z1-14 needs to see the player character right away, the player character can go and finish Operation Ticonderoga and return to Z1-14 after it is complete.
* Even if the player character completed most of this quest (up until the objective "Keep working with Father") and is still allied with the Railroad, should the player become Banished from the Institute and begin working with the Minutemen to take down the Institute, Z1-14 will be hostile and will fight the player character alongside Institute forces during The Nuclear Option (Minutemen). There is no option to warn Z1-14 or ally him with the Minutemen's fight against the Institute. There are no friendly rebel synths. Triggering the evacuation has no effect on Z1-14.
* X6-88 hates almost every move the Sole Survivor does in this quest, and will become hostile if they attack the guards, which makes the Sole Survivor an enemy of the Institute.
* Completion of this quest will allow legendary variants of the railway rifle to be found randomly as loot on legendary enemies.
** The console command will enable them to be looted if one cannot, or does not wish to, complete this quest.
==Behind the scenes==
Cut content for Institute SRB indicates that one ending (if not the ending) for this quest would have involved Z1-14 escaping the Institute on his own, and/or being caught by the Synth Retention Bureau. An unused Institute terminal associated with a location marker in the SRB (and a separate unused entry on a non-cut SRB terminal) reveal details of Z1-14 escaping, to be recaptured pending courser availability. A separate SRB location marker, , indicates that Z1-14 may have been recaptured and imprisoned in the SRB's synth reprogramming cells. The quest stages associated with the terminal (and likely also these events) are 1300, 1400, and 1600, all of which have been removed from the quest entries and provide no further details.
==Bugs==
Category:Railroad quests
Category:Fallout 4 quests
Category:Fallout 4 achievements and trophies
es:Tapadera subterránea
pl:Skryci, tajni i podziemni
pt:Subterrâneo Sob Disfarce
ru:Под землёй и под прикрытием
uk:Під землею і під прикриттям
zh:地底潛入行動