Follow the synth and High Rise to Ticonderoga, eliminating the opposition along the way.
Talk to High Rise once you arrive.
Return to Doc Carrington.
Give Carrington his prototype
My first official assignment in the Railroad is to deliver Doctor Carrington the prototype we recovered from Switchboard. And then see if he needs any help.
Retrieve the dead drop
For my first job I have to help out H2-22, a Synth who is in trouble at Bunker Hill. Railroad HQ doesn't have many details. I'm to proceed to pick up a dead drop left by Old Man Stockton.
Meet Old Man Stockton
Old Man Stockton is ready for contact at Bunker Hill. Perhaps now I can see how I can help H2-22.
Secure the rendezvous point
Wait until night time for Old Man Stockton
Wait for Railroad contact
Old Man Stockton has lit a signal lantern. H2-22 and I need to wait for another Railroad agent to arrive.
Follow High Rise
High Rise, another Railroad agent, needs my help escorting H2-22 to a safehouse called Ticonderoga. Once H2-22 is there, he'll be safe for now.
Talk with High Rise
Report back to Doctor Carrington
I safely got High Rise and H2-22 to Ticonderoga Safehouse. It's time to report back to Doctor Carrington.
Hostile NPCs that are not related to the quest might already exist along the path between the midnight meeting point and the Ticonderoga safe house. Clearing the route in advance can avoid complications.
Although H2-22 is reluctant to talk, if you are persistent and pass some speech checks you can obtain some interesting insight into the miserable life of a synth at the Institute. Despite being instructed by Old Man Stockton not to discuss these details, Stockton will not object if you pursue this line of questioning with H2-22.
Due to the close proximity of a band of Ghouls it's possible that the Raiders in the church may be lured away before you can get to them. Unless you can hunt them down and kill them all this can lead to it not being possible to complete the 'Secure the rendezvous point' objective making the quest uncompletable.
The raiders in the church cannot be killed by companions or through inciting them to attack each other. They will simply be knocked down at low health and get back up after a few seconds, thus making it impossible to complete this quest without killing anyone.