The Motherlode

The Motherlode is a side quest in Fallout 76. This quest can be discovered while exploring Hornwright Industrial headquarters.

Detailed walkthrough
There are two ways to enter the headquarters. When getting close, there will probably be some mutants and Scorched killing each other. You can clean up the outside of the building and work your way to the top entrance or there's an entrance on the bottom floor that enters into the lobby. In the lobby of the Hornwright Industrial HQ is an office belonging to Yvette Wiesman. Using the terminal and accessing the archived message dated 9.29.77 will finish the explore mission and begin The Motherlode. The water on the floor is highly toxic. The player character will be instructed to search Penny's (Penelope Hornwright - Sr. Ops Exec) office for more information. Her office is about five floors up. There is also an elevator door in this room that the player character will return to. In Penny's office upstairs, there is another terminal to use. Access the archived message dated 9.30.77 to update the mission.

Now the player character will need to acquire an ID card before they can use the elevator in the lobby to reach the upper floors. Go down the stairs one floor, then into the first door on the left. In the back, there is a computer which controls the Hornwright hiring system. Apparently, in order to get an ID card, the player character will need to become an employee. The player character will need to find a resume and submit it but taking the Hornwright senior executive exam is completely optional.

Another terminal in the same room hosts the exam for those wanting to complete the exam. There are five questions on the exam and all must be answered correctly (Number 2 has two correct answers, so either one will work). The answers are in the gallery below.

The next room has a desk where one can find the Senior executive exam updates holotape. Play the tape to update the mission. The exam answers are now available from tech support, one floor down. The sheet is laying on a printer in the office. Go down two more floors (one up from the lobby) to the company archives room and use the terminal inside. Access the human resources database and then Penny's resume file. This will add her resume to the player character's inventory. Go back up to the third level and into the testing room again. Deposit the resume into the resume receptacle.

The connecting room has the ID card printer on top of a file cabinet. Activate it to gain an ID card. Now go back to the lobby and use the elevator to reach the executive floor. Look for a door with a blue laser grid. These are safe to walk through. Activate the external connection system terminal. The computer will request a repair beacon. The location for this information is not marked but is in the room. Look for a set of computers behind the ECS terminal up a short set of steps. Interact with the research terminal and access the research notations, then power struggles. This will give the player character the beacon code (36984).

Use the keypad to put the code into the security box behind the research terminal. This will dispense a repair beacon in the machine to the left. Activate the dispenser to gain the beacon. Leave the room and go to the opposite laser walled room and find the elevator, then take it to the "sub room." The beacon launcher is standing in very toxic water. Use a radiation suit, or Rad-X if needed, to get to the device and activate it. Move out of the way as a drill machine will enter the room through the floor. After it leaves, access the motherlode at the docking station dispenser in the same room. This will end the mission.

Quest stages
{{Quest stage table FO4 It seems Hornwright Industrial was working on a project codenamed "The Motherlode" but I'm going to need to need find a Senior Executive ID to find out more. Apparently I might be able to get one from HR. }}
 * stage1   =?
 * desc1    =Explore Hornwright Industrial HQ
 * log1     =
 * stage2   =?
 * desc2    =Search Penny's office for info about the "Motherlode"
 * log2     =Sound like this Penny Hornwright might be able to help me get to the bottom of this "Motherlode." Maybe if I search her office I can find more information.
 * stage3   =?
 * desc3    =Find a way to acquire an ID to access the upper floors.
 * log3      =It seems I'm going to need to gain access to the Hornwright R&D lab in order to find out more about this "Motherlode," but I can't get in there without a Senior Executive ID. Sounds like I might be able to pick one up in the HR department. OR
 * stage4   =?
 * desc4    =Find a way to impersonate a Senior Executive
 * log4     =Apparently only Senior Executives can print out new ID cards. Great. Maybe there's some way I can trick the system into thinking I'm an exec.
 * stage5   =?
 * desc5    =Find a Senior Executive resume
 * log5     =I've got two options to fake my way into a Senior Executive position - turn in a resume to the hiring system or ace the Senior Executive hiring exam. Maybe they've got an old resume on file I could use? Or maybe a list of the exam answers around here somewhere?
 * stage6   =?
 * desc6    =Pass the Hornwright Senior Executive Exam
 * log6     =
 * stage7   =?
 * desc7    ={Optional) Find the answers for the Senior Executive Exam
 * log7     =I found the answers to the Senior Executive Exam. Hornwright Industrial's about to have a new employee.
 * stage8   =?
 * desc8    ={Optional) Collect the exam answers from Tech Support
 * log8     =
 * stage9   =?
 * desc9    =Search the company archives for an Executive Resume
 * log9     =I found the resume of Penny Hornwright, one of the company's executives. I should turn this in to the hiring system.
 * stage10  =?
 * desc10   =Deposit the resume in the receptacle
 * log10    =
 * stage11   =?
 * desc11    =Return to the hiring system for your results
 * log11     =Looks like I aced the Hornwright Senior Executive Exam. Now I just have to check in with hiring system.
 * stage12  =
 * desc12   =Collect your Senior Executive ID
 * log12    =I've gotten myself registered as a Hornwright Senior Executive. Now all I have to do is print myself an ID and then I can get to the bottom of this "Motherlode."
 * stage13  =?
 * desc13   =Explore the building's upper floor for info on the "Motherlode"
 * log13    =Hornwright Senior Executive ID acquired. Now I should be able to get into the offices on the upper floors.
 * stage14  =?
 * desc14   =Search the lab for information on where to find a Repair Beacon
 * log14    =I spoke to the Motherlode ... I think. It's a robot? It didn't sound like it was in great shape. It asked me to get it a "Repair Beacon." Maybe I can find one nearby.
 * stage15  =?
 * desc15   =Requisition the repair beacon - Code 36984
 * log15    =I found the requisition code for the repair beacon: 36984. Now I just need to plug it in.
 * stage16  =?
 * desc16   =Collect the repair beacon
 * log16    =Repair beacon issued! Now I just need to collect it and I should be able to use it to help the Motherlode.
 * stage17  =?
 * desc17   =Deploy the repair beacon
 * log17    =Repair beacon acquired. It sounds like I'll need to head down the elevator to deploy it to help the Motherlode.
 * stage18  =?
 * desc18   =Collect the Motherlode's gift
 * log18    =It appears the Motherlode left me a thank you present for helping to repair it and said it would be in contact in the future. Friendliest drill I've ever met.
 * status18 =finish

Rewards

 * Iron ore x2
 * Black titanium ore
 * Aluminum ore
 * Iron ore x2
 * Bottlecap x150
 * Silver ore
 * Plan: Combat rifle

Behind the scenes
Motherlode 003 is likely a reference to The Venture Bros's AI character M.U.T.H.E.R. with both using the same voice, sharing the same name, and asking for their creator upon waking up.