Boston After Dark

Boston After Dark is a Railroad side quest in Fallout 4.

Detailed walkthrough
Doctor Carrington asks the Sole Survivor to assist with escorting the newest rescued synth. They must receive a message from Old Man Stockton at the assigned dead drop or head directly to Bunker Hill and talk to Stockton inside the building. He'll respond to the security phrase with the information: that there are raiders at the drop-off location and requests that the Sole Survivor to clear the area. Passing speech checks can get more caps and/or the first mention of "Patriot."

Head to Cambridge church, indicated by the quest marker and eliminate the raiders, then wait until it's night time. Stockton will bring the synth, named H2-22, and give the all-clear sign by lighting a lamp in the window, then he leaves. Talking to the synth doesn't reveal much information since he's been told not to talk to anyone. Passing increasingly harder speech checks reveals that he was a maintenance worker at the Institute, and was treated no better than a tool.

After some time, a Railroad operative called High Rise arrives and after a brief conversation, he advises the player character there are raiders en-route to the safehouse. The Sole Survivor and High Rise will then proceed forward with H2, fighting through the raider outpost. Upon reaching Ticonderoga, they will thank the Sole Survivor for the assistance, and the location will be usable as a safehouse from then on. Speaking to the synth reveals he is scared but hopeful about his future.

Return to Carrington to receive a reward and the next quest.

Bugs

 * If you head to the church to "secure the rendezvous" and the raiders are dealt with, Stockton may not arrive, leaving the quest unable to be completed.
 * Using the console, the quest can possibly be advanced using a series of steps. First, make sure the quest is at the correct stage using and stand in the church at the quest marker. Then, teleport H2-22 to you with . If he doesn't appear, then enable him with . Let H2-22 take up his position in the church, but if he tries to run away then simply skip to the next step and repeat the previous step. Next, teleport Old Man Stockton to you in the church with  and be wary that he might try to run away back to his market stall in Bunker Hill. Finally, with both characters now present in the church and H2-22 being enabled and visible, quickly speak with Old Man Stockton before he has a chance to possibly run away and the quest should continue as normal.
 * Upon arriving at the church, you may discover two raiders inside and one feral ghoul outside (or already killed by two raiders). After killing the raiders and ghoul, the quest still may not progress and your objective will remain "Secure the rendezvous point." The quest requires that you kill three raiders to advance to the next stage and the ghoul mistakenly spawns in place of a raider. This bug makes it impossible to complete the quest on Xbox. On PC you could use the console to resurrect and kill again one of the raiders and the quest will move to the next stage as expected.
 * It's possible to pick up the Augusta report and start Butcher's Bill before reporting back to Carrington. If you complete Butcher's Bill as well, you can no longer hand in Boston after Dark. Carrington will only have his generic dialogue.
 * This can be avoided by loading a save before the glitch occurred, and allowing him to talk to you first instead.
 * Using the console, the quest can be completed with.
 * Stockton and H2-22 may also arrive during daytime.
 * Stockton will go to the lamp to light it for the signal but the lamp won't actually ignite.
 * The raiders in the church cannot be killed by companions or through inciting them to attack each other. They will simply fall down at low health, getting back up after a few seconds.