The Secret of Cabot House

The Secret of Cabot House is a side quest in Fallout 4.

Detailed walkthrough
When returning to the Cabot House after saving Jack's sister, the player character will get this mission assigned by Jack to help prevent raiders from freeing Lorenzo. Although one can actually fail in preventing the raiders from freeing Lorenzo, the Sole Survivor still has to kill them all once Lorenzo is released.

OR
 * Upon flipping the switches and killing Lorenzo, Jack tells you Lorenzo would have killed his family as well as the player. He says his family influence was the only thing keeping his father in the asylum as opposed to Death Row due to his crimes during his life. Jack says that now that the world is "built for monsters", nothing would have stopped his father from presumably returning to criminal activity. You can choose to thank him or berate him for being sad only because he "lost [his] mortality juice"; though Jack seems to genuinely believe he could have removed the artifact and cured his father with a little more research. He awards you with about 500 caps and tells you to return to his home in about a week. He gives you a slightly different amount of caps depending on what you say following killing his father.
 * When an in-game week has passed, you will receive a notification that tells you to visit Jack back at the asylum. He tells you he figured out how to access the telekinesis effect of the artifact. He gives you Lorenzo's Artifact gun.


 * Choosing to save Lorenzo by pushing the switch by his door will prompt Lorenzo to leave his cell; him saying he wants to have a "long overdue" conversation with his son. He tells you "we'll have to kill him, you know. And the rest of them." He tells you his son trapped him in there in 1898; nearly 400 years before the in-game date.
 * Arriving to Cabot house, Jack will ask why you freed him. The next conversation options will allow you to either help Jack further by saying you can help him, or help Lorenzo by saying he is wrong and then killing the Cabots. Whatever you choose to say, Lorenzo will appear on the balcony overlooking the family room. Wilhelmina tries to sell Jack out by saying she would never allow him to do what he did, but Lorenzo berates the family for feeding on his blood. Lorenzo then turns hostile to the Cabots (and the Sole Survivor if that option is chosen).
 * After killing him, Jack will reward you 502 caps, saying he no longer needs your services. Every quote from him following quests' end either mourns his lost family or berates you for not listening to him.
 * (If however successful in keeping every family member alive, asking for more rewards allows you to come back in a week to receive Lorenzo's Artifact gun.)
 * Otherwise, after killing the Cabot family, Lorenzo will offer a "lifetime supply" of Mysterious serum, i.e., one at a time, which cannot be sold or traded away.

OR


 * The following describes the details for Plan C in which you free Lorenzo and then kill him before he leaves the area that is outside his cell.
 * You can activate up to 3 switches and still open the door of Lorenzo's cell to let him out.
 * Once he is out you can speak with him to find out what he intends to do.
 * Then you can engage and kill him pretty easily. Just stay out of his melee and "force push" range and shoot him until he dies. His "force push" doesn't do a lot of damage if your damage resistance is over 115 or so but it does stagger you and it prevents you from aiming properly for a moment. Lorenzo's gun is a low damage pipe pistol that doesn't do very much damage. Lorenzo does have a lot of health so it will take some time to kill him if you don't feel like wasting explosives or high-damage ammo on him.
 * Return back to Cabot house and Jack will be upset that you set Lorenzo free, but then you can tell him that you killed Lorenzo and that you are sorry that you did so. He will give you the 500 (or so) caps.
 * After a week you can return and Jack will give you Lorenzo's Artifact gun.

Regardless of your choice above, when finished on the floor with Lorenzo's cell, don't try to leave the asylum by retracing your steps. Doing so will lead to a dead-end under the room you dropped from on the way down. Instead, use the elevator in the control room to return to Cabot's office.

Bugs
Тайна дома Кэботов