Brain Dead

Brain Dead is a side quest in the Fallout 4 add-on Far Harbor.

Synopsis
A Miss Nanny has appeared in Far Harbor, searching for a law enforcement official to carry out an investigation into a murder at a local hotel. Of course, things are not as obvious as they seem and soon, the trail leads to Vault 118 beneath the Cliff's Edge Hotel...

Walkthrough

 * 1) Talk to Pearl in Far Harbor on your return visit from Acadia. Agree to act as investigator and meet her at the Hotel.
 * 2) Optional: There are several persuasion checks to receive several stacks of pre-War money as advance payment and retainer, as well as try and pry the identity of her employers out of her.
 * 3) Fight your way through the hotel and the ghouls roaming inside, following Pearl to the elevator at the top floor.
 * 4) Enter Vault 118 and talk to Maxwell, who starts the quest proper.
 * 5) Investigate the crime scene in the ball room: The smashed brain containment unit, the blood trail, which turns out to be red paint, and the Fencebuster by the wall. Once you have all three, talk to Maxwell.
 * 6) Investigate the suspects: Santiago Avida and Keith McKinney.
 * 7) Santiago is in the generator room. Talk to him about the case and he will suggest interrogating Julianna Riggs, if asked about the paint, Santiago will mention Ezra borrowing his last one, which he can't find.
 * 8) McKinney is in his room, practicing his lines with Gilda. He will point to Santiago.
 * 9) Talking to Bert Riggs and Julianna Riggs will highlight the Overseer's office as a stopping point.
 * 10) Head to Ezra's quarters (next to the little museum/shrine he made for himself) and pick up the Vault 118 key, then go to the Overseer's office, accessible through the upper floor. Access the terminal and listen to the holotape to learn of Ezra's embezzling.
 * 11) Talk to Bert Riggs about Julianna (mentioned in the holotape). If pressed through two persuasion checks, he will reveal that Julianna Riggs is not who she says she is, as she was, quote, a very harsh woman. Politeness wasn't her deal.
 * 12) Confront Julianna Riggs... Or should we say, Ezra Parker? Turns out, the con man planned to use the Vault as a get-rich scheme, embezzling funds. When Riggs confronted him over the issue, he killed her, traded places posing as Bert's wife to squeeze just a little more money out of the Vault, then make a get away.
 * 13) Optional: Extort Ezra/Julianna for 250 pre-War money stacks.
 * 14) Decide: Either punish Ezra/Julianna on the spot or allow him to get away unpunished. The former will result in him attacking you. The latter will cause Ezra/Julianna to slowly roll towards the entrance. You can still go to Maxwell and accuse Ezra of the murder, which will cause the Vault to turn on him and likely kill him. The end result is the same:
 * 15) Case closed

Behind the scenes

 * The structure and plot of Brain Dead borrows heavily from the Fallout: New Vegas mod Autumn Leaves created by BaronVonChateau.