As ordered earlier, go see Lance Captain Kellis for your next mission. Once you do, he will tell you about the Railroad and how they have decided to pre-emptively take them out as they pose a threat to further Brotherhood operations. You can try to argue against it if you want, but it is decided and you can't change it at all. You will shortly become enemies with the Railroad afterwards, losing your ability to fast travel to the Railroad HQ in the meantime.
you are told to meet the team at the Old North Church to lead the strike against the Railroad and to try and decrypt P.A.M. so the Brotherhood can use it themselves (or destroy it if you can't do that). You are then given the "Priority Kill Orders" to make sure the Railroad Leadership is wiped out and the "P.A.M. Decryption Program" to take over P.A.M. In case you were curious, the leaders of the Railroad you need to kill include Desdemona, Tinker Tom, Deacon, Doctor Carrington and Glory.
Old North Church
Travel to the Old North Church and head inside, where you will undoubtedly already hear the fighting begin. The Railroad has agents up on the second level here, so get under the balcony right away and start picking off whoever you can. Doctor Carrington is actually here, so be sure you take him out and wipe out everyone else, making your way upstairs as you go. Wipe them out and head down into the catacombs.
In the catacombs make your way forward and help the Brotherhood members clear out the resistance. Use the many nooks here for cover if needed and watch out for grenades as you continue. Fight your way to the "Railroad" puzzle/door where, thankfully, you do not have to input the password again. You can just activate the explosive device that your allies place on the wall to blast your way in, then clear out the guards in front of the Railroad HQ. Once you've done that you can enter the headquarters to continue the slaughter.
Note: If you had Deacon as a companion and put him out in a Settlement somewhere, he will return automatically to the HQ. In fact, you may run into him in the church.
This part is a bit rougher, as your Brotherhood allies can't seem to open doors and join you. Bah! You will be bombarded as soon as you enter, so equip and chuck some grenades out in the middle and take cover over in the right-hand corner (use the brick strut here to hide behind for cover). Locate and take out Glory, Tinker Tom and Desdemona from here. Tinker Tom is easy to take out, but Glory will be fighting with a Mini-Gun so take her arms out. Desdemona is nothing special either, but does attack with a Railway Rifle which should be looted once she is dead (if you haven't gotten one of these yet they shoot spikes and are generally awesome). You can also loot the "Railroad HQ Key" from her body.
Once all of the enemies are dead, be sure to visit P.A.M. and use her computer. Upload the P.A.M. Decryption Program Holotape and start the decryption process. This will reset P.A.M. and let the Brotherhood take her over. With all of that done, head back to the Prydwen and talk to Lance Captain Kellis to report your success. He will be highly pleased and tell you to go talk to Proctor Ingram, who has asked for you. This ends this mission and starts the next Brotherhood of Steel quest "Spoils of War" .
|For derailing the Railroad||590 XP|