Brain Dead

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

Detailed walkthrough
While roaming around Far Harbor, in the Fallout 4 add-on Far Harbor, you will be approached by a Miss Nanny named Pearl. She will then ask you if you're part of law enforcement, mentioning that there's been a terrible murder. Upon confirming she will then ask for you to follow her as the murder has taken place at Cliff's Edge Hotel.

Upon reaching the location she will mention that the residents have been rowdy and that she's had to get physical with some of them as they were getting too "touchy". She will then tell you how the elevator is not working and thus you must take the long way around. During this time she will lead you up through the hotel and back to an elevator only to be used by the special guests. Through this path you will stumble upon several different Feral Ghouls.

Once out of the elevator you will be prompted to speak to a Mister Handy named Maxwell through an intercom which is revealed to be vault door controls. Once done speaking you will be ushered in and escorted to the crime scene. The victim of the murder is presented as Ezra Parker, the owner of the hotel. Upon investigating of the crime scene you will see a bat, red paint to represent blood, and the broken brain incubator.

You will then be asked by Maxwell to investigate the fellow Robobrains living in the vault. The characters you will want to focus your attention on are Julianna, Santiago, and Keith. Through investigating and talking with Bert, Julianna's husband, it will be revealed that she's been acting very different. When confronted Julianna will reveal that she is actually Ezra. It had turned out that Ezra was embezzling the money given by Julianna and when she found out she confronted him. After the confrontation Ezra killed and impersonated her.

You will then be given the decision to either take a bribe or continue on with the accusation which will result in a fight between Ezra and yourself. If you take the bribe you can turn around and continue with the accusation, if you don't you will then begin Brain Dead Pt. 2

Once beginning Brain Dead Pt. 2 you will be given 2 choices. You can return to Maxwell immediately and tell him of Ezra, causing the robots to attack him. Or you can wait for him to leave. Once he's gone, return to Maxwell and tell him how Ezra is the killer. You can then tell 1 of 3 lies, He got away, you killed him, or it's over. No matter which choice you take Maxwell will pay you for your work.

Bugs
It is possible for Pearl to become stuck at the elevators, without saying the line about them being out of order. Leading her away and letting her return did not fix it - currently it seems loading is the only fix.