The Lost Patrol

The Lost Patrol is a quest that can be obtained within the Commonwealth, in Fallout 4.

Synopsis
Before Danse and his team were sent into the Commonwealth, a prior recon team had been sent in three years before. All contact with them was lost, and the recon team presumed dead. Now, by following a trail of blood and unwavering duty, the truth can finally be discovered as to the recon team's fate.

West Everett estates

 * 1) Upon reaching the estates, the Sole Survivor will discover a distress signal, which can be picked up by the Pip-Boy. Following the ping leads to the site of a devastating battle.
 * 2) Inside a burned-out building, the corpses of a number of Brotherhood of Steel soldiers will be found, including the corpse of Knight Varham, who is clutching his personal holotape and holotags.
 * 3) By listening to the holotape or reporting its finding to Kells or Danse, it is revealed that the soldiers found there killed themselves and destroyed their power armor to keep the technology out of enemy hands, with the next clue as to possible survivors leading to the National Guard training yard.

National Guard training yard

 * 1) Once reaching the training yard, the Sole Survivor will find that the area has been overrun with feral ghouls guarded by defense turrets. The player must fight or sneak into the recruitment offices, following Knight Astlin's distress signal.
 * 2) Knight Astlin will be found dead, and must be looted for her personal holotags and holotape. The holotape may then be listened to or reported to Kells or Danse, which will reveal the next clue somewhere near the Revere satellite array.

Revere satellite array

 * 1) After fighting or sneaking through the super mutants at the Revere satellite array, the Sole Survivor will find the corpse of Scribe Faris, who must be looted for his personal holotape and holotags. Listening in to the holotape or reporting its finding to either Kells or Danse, will reveal the final clue for the last known member of the recon team: Paladin Brandis.

Recon bunker Theta

 * 1) The holotape from Faris will reveal a code that was used by the recon team to access a pre-War bunker as a fall-back plan in case their mission went awry. Travel to the bunker, where Paladin Brandis is found to be still be alive.
 * 2) Brandis is understandably shaken up due to his years of isolation and paranoia, initially mistaking the Sole Survivor as a threat. At this point, the Sole Survivor may:
 * 3) Kill him, whether intentionally, or by failing the Persuasion checks.
 * 4) Speak his name, in which Brandis will believe the Sole Survivor's story, and the conflict will be ended peacefully.
 * 5) Through persuasion, Brandis can be convinced that the Sole Survivor is not there to harm him, and the conflict will be ended peacefully.
 * 6) So long as the conflict is ended peacefully, Brandis can be given the holotags of his fallen brothers and sister, for closure.

Conclusion

 * 1) Should Brandis have to be killed, his holotags will need to be brought back to Kells.
 * 2) Should the conflict with Brandis be brought to an end peacefully, the Sole Survivor will have the option of either leaving him back at the bunker, or convincing him to rejoin the Brotherhood of Steel.
 * 3) Convincing Brandis to rejoin the Brotherhood of Steel will see to his return to the Prydwen, and he will be seen fighting with the Brotherhood of Steel during future conflicts.
 * 4) If the Sole Survivor turns the quest in to Kells, he will reward the player with the unique Steadfast BOS combat armor chest piece.