The Big Dig

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The Big Dig is a side quest in Fallout 4.

Quick walkthroughEdit

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 walkthroughEdit

The player character receives the quest after talking to a woman named Bobbi No-Nose in a backstreet at Goodneighbor. She says that she's planning a job that requires discretion, not sharing many details at first. The player character needs to go down in The Dig, a tunnel starting at Bobbi's house basement and help diggers fight 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 and wants help in freeing an old associate, Mel, from the security office.

There are several ways to free Mel: pickpocket a key, steal a key from the nearby office, hack the nearby protectron to kill the guards, or bribe the guard nearest him or passing a medium or hard persuasion check. (It may be difficult to find the right guard as there are no distinguishing characteristics.) Crimes will of course result in security becoming hostile (as well as your active companion, possibly), but using dialogue will not turn them hostile (even if the threaten check fails). To the left of the cell is the office, inside 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. If the guards spot you they will become hostile. Tell Mel about the job and meet him at The Dig.

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 player's first chance to tell Sonya where to blast, it is possible to blow open the wrong path, leading to a dead end with a mirelurk king as well as 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 with the sacrifice of Sonya, it is revealed that it's not Diamond City's strongroom but a secluded storage room at NH&M Freight Depot owned by John Hancock, Goodneighbor's mayor.

The room is filled with the mayor's henchmen. The player character should be 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; if the player character enters the room wearing headwear incorporating a targeting hud, Fahrenheit and her men will be automatically hostile, forcing the PC to kill them to continue. If you still have the headwear on 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 (+15 fire damage); Ashmaker. Additionally, John Hancock will become available as a follower.

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

Quest stagesEdit

10 Talk to Bobbi
20 Meet Bobbi inside
25 Join the dig
35 Exterminate the Mirelurks (3/3)
40 Talk to Bobbi
45 Meet Bobbi in Diamond City
55 Get Mel Out of Jail
58 Recruit Mel
60 Meet the gang in the Dig
70 Dig to the 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 men
220 Kill Bobbi
225 Talk to Fahrenheit
235 Open the train car
238 Get paid
260Quest finishedIcon checkQuest complete - Sided with Bobbi
270Quest finishedIcon checkQuest complete - Sided with Fahrenheit


  • This quest is required to unlock Hancock as a companion.
  • 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". Returning to Security the player will then find Mel outside his cell, without the guards becoming hostile.
  • If frustrated, Berry Mentats can help in the jailroom.
  • After Mel's robot blows the first hole in a wall, head straight ahead in the room with 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 the player 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. To recover the frame, you can either shoot the fusion core in the back until is depleted and falls out, exploding; or you can pickpocket the fusion core. Either way, the NPC will get out, and you can now reclaim the power armor.
  • There are two routes to the basement. One is filled with mirelurks, the other with ghouls. The start of this route is a bit more hidden. You can find the start by standing in front of the Port-A-Diner in the subway station and looking at the wall to your left, near the Nuka Cola machine.
    • Before blowing the last fragile wall, you can go back to do the other route for more loot.
  • 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.
  • This quest can also be started in a random encounter, when a gangster approaches you and tells about some easy money. He directs you 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 you enter from below, conveniently discovering the NH & M Freight Depot location if you haven't done so already. This allows you 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.
  • Inside Hancock's locked train car, there is a set of blocks under the shelf next to his sleeping bag that spell 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.
  • Bobbi No-Nose can randomly acquire a Legendary weapon from the many mirelurks or feral ghouls you fight your way through to reach the storeroom, which can increase her combat effectiveness, and also make her a more difficult opponent if you end the quest by fighting her.
  • After resolving the standoff peacefully, passing a speech check, and sending Bobbi No-Nose home, the two triggermen with remain at the strongroom location and non-hostile towards the player and will stay so as long as the quest isn't completed.

Behind the scenesEdit

  • 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
  • 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.


  • ps4Icon ps4 pcIcon pc xboxoneIcon xboxone Bobbi's 3rd floor terminal in Bobbi's place may not allow you to sit down to hack, resulting in the safe being impossible to open [verified]
  • ps4Icon ps4 pcIcon pc xboxoneIcon xboxone Trying to talk to Bobbi through the door may not work, preventing the Sole Survivor from continuing the quest. 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 targetted and not a dust cloud, "setscale 1" to undo).[verification overdue]
  • xboxoneIcon xboxone ps4Icon ps4 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 you're 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.[verification overdue]
  • xboxoneIcon xboxone pcIcon pc ps4Icon ps4 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]
  • xboxoneIcon xboxone 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.[verification overdue]
  • xboxoneIcon xboxone ps4Icon ps4 pcIcon pc Sonya may occasionally get stuck in walls or objects during fights, terminal accesses and other events, preventing her from removing walls. You 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 click her and enter 'moveto player', or, if she can not be clicked, first use 'prid 11fc2e' to teleport her to you.[verification overdue]
  • xboxoneIcon xboxone Sometimes Mel can be made permanently aggressive to the player, making it impossible to destroy the ceiling below the strongroom.[verification overdue]
  • pcIcon pc ps4Icon ps4 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.[verification overdue]
  • ps4Icon ps4 xboxoneIcon xboxone 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 fix this.[verification overdue]
  • pcIcon pc ps4Icon ps4 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 you to walk through the wall. The NPCs will follow you through.
  • pcIcon pc xboxoneIcon xboxone 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.[verification overdue]
  • xboxoneIcon xboxone ps4Icon ps4 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.[verification overdue]
  • pcIcon pc xboxoneIcon xboxone ps4Icon ps4 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]
  • xboxoneIcon xboxone Wearing gear upgraded with Ballistic Weave can also make Bobbi and Fahrenheit turn against you.
  • pcIcon pc John Hancock will ask you to "Confront Bobbi" if you sided with Bobbi No-Nose and killed Fahrenheit during The Big Dig side quest upon returning to Goodneighbor. Upon arriving at Hawthorne Estate, she will ignore the player, thus preventing the player from obtaining Hancock as a companion.[verification overdue]
  • pcIcon pc 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.[verification overdue]
  • pcIcon pc Hancock might initiate his dialogue apologizing for making the Sole Survivor confront Bobbi No-Nose without completed the quest to begin with.[verification overdue]
  • pcIcon pc Sometime Mel will disappear or Sonya will get stuck, simple workaround run back to the entrance and stare at any wall for a bit and they will reappear/unstuck.[verification overdue]
  • ps4Icon ps4 pcIcon pc On the last door, Mel and Sonya tend to break, and will not remove the wall. (PC: Works to leave the tunnels go back to the last room and sleep for a hour (sometimes))[verification overdue]
  • xboxoneIcon xboxone The door to the strongroom may be bugged preventing player to enter.[verification overdue]
  • ps4Icon ps4 The last fragile wall may not be accessible. Pressing X to activate it does nothing.[verification overdue]

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