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The Big Dig is a side quest in Fallout 4.

Quick walkthrough

Side quest: The Big Dig
Meet Bobbi inside.
Join the dig.
Exterminate the 3 Mirelurks.
Talk to Bobbi.
Meet Bobbi in Diamond City.
Get Mel out of jail.
Recruit Mel.
Meet the gang in the Dig.
Meet with the gang in the basement.
Get out of the basement.
Enter the Strongroom.
Side with Bobbi.
Side with Fahrenheit.
Reward: 300 XP
300 caps
Ashmaker on Fahrenheit's corpse.
Reward: 300 XP
Ashmaker given by Fahrenheit
Leads to: Kill Bobbi

Detailed walkthrough

The Sole Survivor receives the quest after speaking to Bobbi No-Nose in a backstreet in Goodneighbor. She says that she's planning a job that requires discretion, not sharing many details at first. From here, one needs to go down into the Dig, a tunnel starting at Bobbi's house basement, and help the diggers fight the mirelurks. After, she asks the player character to meet her in Diamond City, where she reveals her plan to break into the Diamond City strongroom under the mayor's office. In order to do this, Bobbi requires assistance in freeing an old associate, Mel, from the security office.

There are several ways to free Mel: talk to Mel, then simply wait until the current day has passed (Mel will make a snide comment that Bobbi couldn't even wait a day), pickpocket a key, steal a key from the nearby office, hack the nearby protectron to kill the guards, bribe the guard nearest him or convince the guard to let Mel go by passing a medium or hard persuasion check. The guard that can be bribed or persuaded is the one that moves around between Mel and the office nearest to the jail.

Crimes will of course result in security turning hostile (and possibly one's active companion), however, using dialogue will not turn them hostile (even if the threaten check fails). To the left of the cell is the office, inside the Survivor can steal the key from the desk, then sneak to the right side of the cell. When the guards are not looking unlock the cell with the key and meet Mel outside. Tell Mel about the job and meet him at the Dig.

Once gathered at the dig site, Mel has prepared an eyebot named Sonya to blow through soft walls in the tunnel with sonic resonance. The group begins traveling through old metro stations and basements filled with feral ghouls and more mirelurks. At the first available opportunity to tell Sonya where to blast, it is possible to blow open the wrong path, leading to a dead end with a mirelurk king and a leveled set of power armor.

Mel will frequently express his doubts about the tunnel actually leading to Diamond City, that the team is heading too far south. After they make it to a cavity underneath the strongroom and blow the ceiling, sacrificing Sonya, it is revealed that it's not Diamond City's strongroom but a secluded storage room at NH&M Freight Depot owned by Hancock, Goodneighbor's mayor.

The room is filled with the mayor's henchmen. The player character is subsequently given the choice to persuade Bobbi to leave and surrender, kill all the guards and stay with Bobbi, or betray Bobbi and kill her for the mayor instead. Note, if the player character enters the room wearing headwear incorporating a targeting HUD, Fahrenheit and her men will be automatically hostile, forcing the player to kill them to continue. If the headwear is still worn after finishing the quest by getting paid, Bobbi will also immediately turn hostile and attack.

If the player character persuades Bobbi to leave or betrays her, Fahrenheit will reward them with a legendary minigun with incendiary bullets, Ashmaker. Additionally, Hancock will become available as a follower.

Even if the player character kills Fahrenheit and sides with Bobbi, Ashmaker can be looted from Fahrenheit's corpse and Hancock will still be available as a follower after finishing Hancock's follow up quest of killing Bobbi.

Quest stages

Quest stages
StageStatusDescriptionLog Entry
10 Talk to Bobbi
20 Meet Bobbi No-NoseI met Bobbi No-Nose in an alley in Goodneighbor and agreed to work for her. She hasn't told me much about the job.
25 Join the digI met Bobbi No-Nose in an alley in Goodneighbor and agreed to work for her. She asked me to work on digging a tunnel in her basement.
35 Exterminate the Mirelurks (3/3)
40 Talk to Bobbi
45 Meet Bobbi in Diamond CityBobbi promoted me after I exterminated a group of Mirelurks in her basement. She asked me to meet her in Diamond City to tell me more about the job.
55 Get Mel Out of JailBobbi revealed that we are digging to the Diamond City strongroom to steal what's inside. She asked me to recruit a man named Mel who is locked up in Diamond City Security.
58 Recruit Mel
60 Meet the gang in the DigI broke a man named Mel out of Diamond City Security. Now I need to meet up with Bobbi in the tunnel and start digging to the Strongroom.
70 Dig to the StrongroomMel brought a robot to help with the dig. Now all we have to do is use it to dig our way to the Diamond City strongroom.
95 Dig through the subway area
150 Dig through the basement area
160 Meet with the gang in the strongroom basement
175 Get out of the basement
180 Enter the Strongroom
210 Kill Fahrenheit and her menBobbi lied. We were not digging to the Diamond City Strongroom. Instead we ended up breaking into Hancock's strongroom. His bodyguard Fahrenheit confronted us and demanded we leave.
215 Bobbi lied. We were not digging to the Diamond City Strongroom. Instead we ended up breaking into Hancock's strongroom. His bodyguard Fahrenheit confronted us and we ended up killing her.
220 Kill BobbiBobbi lied. We were not digging to the Diamond City Strongroom. Instead we ended up breaking into Hancock's strongroom. I confronted Bobbi and she got violent.
225 Talk to FahrenheitBobbi lied. We were not digging to the Diamond City Strongroom. Instead we ended up breaking into Hancock's strongroom. I confronted Bobbi and killed her.
230 Bobbi lied. We were not digging to the Diamond City Strongroom. Instead we ended up breaking into Hancock's strongroom. After being confronted by Hancock's guard, I talked Bobbi into abandoning the job.
235 Open the train car
238 Get paid
240 We dealt with Hancock's bodyguard and found his loot in a locked up train car. Bobbi paid me for a job well done.
250 Fahrenheit thanked me for not letting Bobbi steal from Hancock's strongroom. She asked that I speak to Hancock in person.
260Quest finishedQuest complete - Sided with Bobbi
270Quest finishedQuest complete - Sided with Fahrenheit

Companion reactions

Accepting the questLike????N/ALikeNo reaction?Like???No reaction
Bribing guard to release Mel?No reaction??LikeN/ALikeDislikes?????No reaction
Threatening guard to release MelLikeDislikes??DislikesN/ALikeDislikes?????No reaction
Sticking with BobbiLikeDislikesDislikes?DislikesN/ALikeDislikes?????No reaction
Betraying BobbiLikeDislikesDislikes?DislikesN/ALikeDislikes?????No reaction
Trying to convince Bobbi to leave peacefullyDislikesLikeLike?LikeN/ADislikesLike??Like??No reaction
Ending the quest after siding with Fahrenheit????LikeN/ANo reaction???????
Ending the quest after siding with Bobbi????HatesN/ALike???????
Attacking Bobbi following completion of the quest (having previously sided with her)????LikeN/ALike???????


  • This quest is required to unlock Hancock as a companion.
  • Normally Bobbi will open the slot in the alley door and initiate a conversation with the Sole Survivor as they approach her door (no interaction with the door necessary). If the Sole Survivor is already in Hancock's employ to investigate Pickman Gallery however, this might not happen, and interacting with the door will only result in the feedback that a key is required.
  • When attempting to free Mel by releasing the protectron to kill the Diamond City Security guards, the protectron may not win, especially if the guards are high level e.g. 50. In this case, however, talking to Mel and then exiting Security to the main part of Diamond City will nonetheless advance the quest to "Recruit Mel". Upon returning to the security office, the Sole Survivor will then find Mel outside his cell, without the guards turning hostile.
  • After Mel's robot blows the first hole in a wall, head straight ahead in the room with a fusion core generator with no gate. There is a wall that the robot can remove. Behind it, the player will encounter a mirelurk king and an incomplete set of leveled power armor. Mel will then tell the Sole Survivor to turn back into the room the Sole Survivor visited before to blow up another wall. That wall is located in the southwest of the room, as Bobbi explains and will lead to the storage room.
    • If one decides to use the power armor but then exits the suit before the end of the quest, Mel or Bobbi may equip the suit, effectively removing the possibility of retrieving that particular power armor frame.
  • There are two routes to the basement: one filled with mirelurks and the other with ghouls. The start of the latter route can be found by standing in front of the Port-A-Diner in the subway station and looking at the wall to the left, near the Nuka-Cola machine. There are fragile walls between the two routes that connect them, which Sonya can blow open.
    • Many of the mirelurks and ghouls killed here will contain a "Viable Blood Sample", if the unmarked Blood Bank quest has been started.
  • After reaching the last fragile wall, the Sole Survivor must talk to Mel and select the "I'm Ready" dialogue option, and Sonya will blow through the wall. Activating the wall might not work. Once the last wall has been blown, one cannot return to the dig site.
  • This quest can also be started in a random encounter when a gangster approaches the player character and tells them about some easy money. He directs the player character to Bobbi, starting the quest.
  • After blasting through the floor of the strongroom, it is possible to march right past Bobbi and Fahrenheit's conversation and exit the door in the corner opposite where one enters from below, discovering the NH & M Freight Depot location if one has not done so already. This allows the player character to return and finish the quest at a more optimal time, such as after completing another quest involving Hancock.
  • Cait, Strong and MacCready will dislike persuading Bobbi to leave. Cait and MacCready will, however, approve of both betraying and siding with Bobbi. Codsworth, Curie, Deacon, Piper and Nick Valentine like attempting to persuade Bobbi, but dislike betraying her if this fails; shooting Bobbi right after a failed attempt will prevent this. Danse doesn't like betraying or sticking with Bobbi.
  • Cait, MacCready like threatening the guard to get Mel out of jail.
  • Inside Hancock's locked train car, there is a set of blocks under the shelf next to his sleeping bag that spells out "Hancock."
  • If activating the Port-a-Diner in the main subway station, Mel will comment that he won't trust anything looking so preserved after 200 years.
  • In the last room before the storage, where the radioactive barrels are lying on the ground, Bobbi will say that "it's no flesh off my face", but the human party members should stay out of the radiation.
  • After resolving the standoff peacefully, passing a speech check and sending Bobbi No-Nose home, the two Triggermen will remain at the strongroom location, non-hostile towards the player character and will stay so as long as the quest isn't completed.

Behind the scenes

  • The Big Dig was created by level designer Justin Schram, who also created the Dig dungeon itself and wrote many characters for the quest. In creating the Dig, he wanted to have subtle cues that would point the player in the direction they needed to go using rubble and lighting. He also had plans to make the layout and digging mechanic more "Minecraft-y." Though development did not get that far, he was happy with how the quest turned out.[1][2]
  • The quest name is a reference to The Big Dig, a massive public works infrastructure project in Boston that involved the building of various highway tunnels under the Downtown area. The project was famous for its record-breaking cost overruns and the death of a commuter shortly after one of the tunnels fully opened to traffic. Some of the soil removed during construction was deposited on Spectacle Island and used to fill Quincy Quarries.
  • Four wooden blocks spelling the name "Gary" in reference to Vault 108's infamous Gary clones are found in the subway car at the metro station.


  • PCPC Playstation 4Playstation 4 Xbox OneXbox One Bobbi may not initiate conversation through the door, preventing the Sole Survivor from continuing the quest.[verified]
    • PCPC This can be solved by using console command and entering setstage ms16 15 to forcefully skip this stage of the quest. If this does not work then replace 15 with 20, 25 or 30. To open the door that requires a key to unlock, use console command unlock (It may be hard to "target" the door in the console, try using setscale 0 to verify you have the door targeted and not a dust cloud, setscale 1 to undo).
    • A workaround for console players is to use a jetpack and fly to the top of the ruined building left of the door. There is a small gap on the left and if one heads right there is another below. Proceed downwards towards the unrendered Commonwealth where a double door can be accessed to enter into Bobbi’s house. Once inside it is as simple as going out the door again but this time the player character will be behind the locked door, with Bobbi now offering the job which the player character must accept in order for the door to be opened.
  • Playstation 4Playstation 4 Xbox OneXbox One One of the mirelurks during the "Exterminate the Mirelurks (0/3)" part may get stuck behind the first destructible wall and be unreachable, thus making it impossible to continue the quest. Try to leave the room, talk to Bobbi, and re-enter. Alternatively, reloading an earlier save before entering this stage of the quest will fix it. If playing on PC, you may use console command tcl to toggle clipping off, walk through the wall and kill the mirelurk. Use tcl again to turn clipping on again. An explosive may also work.[verified]
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One Mel might be released just when you enter or leave the Diamond City Security building, without the player having undertaken any action to free him. [verified]
  • PCPC Xbox OneXbox One After pickpocketing the guards and freeing Mel, Mel may become unresponsive and the quest will not be able to be completed. This can sometimes be fixed by reloading multiple times, and waiting for Mel to leave the security office before the player character.[verified]
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One Sonya may occasionally get stuck in walls or objects during fights, terminal accesses and other events, preventing her from removing walls. One can walk into her to move her, reload an earlier save or leave and re-enter the tunnels to get her out again. If playing on PC, you can enter 11fc2e.moveto player to teleport her to the player character.[verified]
  • PCPC Playstation 4Playstation 4 Mel may disappear along with Sonya during the quest, making optional walls unable to be destroyed. Activating walls related to the quest will have the walls reappear.[verified]
  • Playstation 4Playstation 4 Xbox OneXbox One When asking to break a wall, Mel will call Sonya but it will just make a quick turn and stop completely, no matter what. Saving, quitting and then reloading can fix this.[verified]
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One When trying to break the final wall, activating it will make Mel glitch and unresponsive. Shoot Mel and then talk to him to resume the quest.[verified]
    • When trying to break down the final wall, it is not able to be knocked down. Instead, talk to Mel to knock it down.
    • If this does not work, you can also use the disable command in the console to disable the wall. Alternatively, using tcl in the console will allow the player character to walk through the wall. The NPCs will follow you through.
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One When entering the strongroom, the option to open the door may disappear, making it impossible to enter. Reloading your game from the main menu usually solves this problem.[verified]
  • Playstation 4Playstation 4 Xbox OneXbox One After killing the guards, Bobbi and Mel will become unresponsive and the quest will not be able to be completed. Reloading an earlier save may resolve this issue.[verified]
  • PCPC Activating the fragile wall location next to a red wall light close to a sleeping bag right before the strongroom basement may result in have Mel getting stuck in front of it a few seconds before disappearing, only to reappear soon after. Activating the wall will not work before talking to Mel.[verified]
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One At several points in the strongroom, Bobbi (and sometimes Mel) or Fahrenheit and her men may suddenly become hostile. The cause may lie with the targeting HUD power armor upgrade. To prevent this from happening, get out of the power armor before entering the strongroom. This bug also appears in Virgil's Cure. [verified]
  • PCPC Playstation 4Playstation 4 When siding with Bobbi No-Nose she may become unresponsive after opening the train cart and only say "Let me check it out first" without ever going to it. To fix it just leave the safe house and re-enter it.[verified]
  • PCPC Sometime Mel will disappear or Sonya will get stuck, a simple workaround is to run back to the entrance and stare at any wall for a bit and they will reappear/get unstuck.[verified]
  • PCPC Playstation 4Playstation 4 On the last door, Mel and Sonya tend to break, and will not remove the wall.[verified]
    • PCPC Sometimes, leaving the tunnels, then going back to the last room and sleeping for an hour will fix the issue.
  • PCPC Xbox OneXbox One The door to the strongroom may be bugged preventing the player character from entering. [verified]


  1. Alumni Guest: Justin Schram From Bethesda Game Studios (reference starts at 19:50)
    Justin Schram: "So, this is my dungeon in Fallout 4, it's called the Big Dig. You explore a subway as you're digging through it, and opening things up. So you can see one of the cues that I have here is this rubble on the subway platform here. It's not subtle, but the player doesn't think about it, the player's not like 'oh, the designer's telling me I need to walk up here so I'm gonna walk up there.' It's just like, it's a subtle cue that this is the way you need to go. Another way we do that is rubble, so you see we have the rubble up in the corner here. The player instantly knows when they see that...rubble's sort of a cue that 'don't go this way.' It's destroyed, it's whatever... so we try to remove a lot of those options subtly. Like, the player doesn't feel limited, the player doesn't feel like we took options away, we're just trying to tell the player 'hey, maybe just don't go this way, it's not that important.'"
  2. Alumni Guest: Justin Schram From Bethesda Game Studios (reference starts at 59:00)
    Justin Schram: "I think I showed 'em here, so the Big Dig, I really like. I got to write a full suite of characters for that, and I had this really cool sort of interactive layout where you're sort of digging your way through. So I really liked that, that was an experiment. It was gonna be much more Minecraft-y. It didn't get that far, but I like how it turned out."