Road to Freedom

Road to Freedom is a Railroad main quest in Fallout 4.

Detailed walkthrough
There are multiple places to acquire this quest, specifically in Diamond City and Goodneighbor. It can be acquired from listening to the Join the Railroad holotape that can be found lying around, overhearing a conversation between two residents of Diamond City near Valentine Detective Agency, talking to Diamond City security inside Diamond City, or by speaking to NPCs who mention the Railroad over the course of the main story (such as Piper and Amari). Any of these actions will trigger the objective to 'Follow the Freedom Trail' to be added to the Pip-Boy, proceed to Boston Common to find the beginning of the trail. Talking to the Tour Bot will provide additional information.

Follow the distinctive red trail of bricks in the ground from location to location. The red line on the ground is largely unbroken but there are a few stretches that are obscured by debris. In these places, the trail is "improvised" using trails of red paint across the street or along with the wreckage of buses and walls. The trail will take the Sole Survivor past several Bostonian landmarks and historical sites, each with a "Freedom Trail" seal outside in the sidewalk, with a letter circled and a number added in red paint. The first seal ("7A") is at Boston Common right near the Tour Bot. The second seal ("4L") is in front of the Massachusetts State House. The third seal ("2A") is at the entrance to the Old Granary burying ground. The fourth seal ("6O") is near the entrance to Goodneighbor (the Old State House from pre-War Boston's perspective). The fifth seal ("3I") is in front of the Old Corner Bookstore. The sixth seal ("5R") is at Faneuil Hall. The seventh seal ("8D") can be found in front of the Paul Revere House. The eighth and final seal ("1R") can be found at the Old North Church, the end of the trail. Following the Freedom Trail isn't mandatory, the Sole Survivor can travel directly to the Old North Church if they already know its location.

Inside the Old North Church, kill a handful of ghouls and follow the lantern painting to find a way down into the catacombs. At the end of the catacombs, there's another Freedom Trail marker with a ring that spins, similar in appearance to the eight seals on the trail. Rotate the outer wheel clockwise and counterclockwise to align the letters with the arrow and press in the center to input the letter. Spell the word "RAILROAD" one letter at a time to open the secret door. The word must be spelled without mistakes. If any mistakes are made, the word must be restarted from the beginning.

Once the door opens and is entered, a blinding spotlight will be shone at the Sole Survivor as they are confronted by the leader of the Railroad, Desdemona, and two Railroad agents, Glory and Drummer Boy, who have their guns readied. Speak with Desdemona - the conversation options will have no effect on the Sole Survivor's future relationship with the Railroad. Eventually, Deacon will enter and vouch for the Sole Survivor, listing two of their major accomplishments in the Commonwealth. Desdemona will ask some further questions including why the Sole Survivor has come to the Railroad, if they know what a synth is, and most importantly if the Sole Survivor would risk their life to save them from their plight.

After all the conversations with Desdemona are done, the quest completes and Tradecraft starts immediately. Hence, to avoid completing this quest and starting Tradecraft, avoid the final conversation with Desdemona. For example, it is possible when contacting the Railroad purely to decode the courser chip, to return to Virgil to obtain the signal interceptor plans without fully completing this quest.

Companion reactions
Companions react to three dialogues with Desdemona: When she asks why you have sought out the Railroad (only when selecting "Fight Institute," the other choices lead to no reactions and is not available if coming to the Railroad with the Courser chip); when she explains how the Institute treats synths ("as tools"); and ultimately, if you would risk your life to save a synth.


 * Fighting the Institute
 * Every companion, with the exception of Curie and Danse, like saying you want to make them pay for what they've done to your family ("Avenge my family"). Curie dislikes it, and Danse has no reaction, despite how he personally detests synths.
 * Nearly everyone will like saying you want to "protect others" from the same fate you've suffered. Curie loves this choice, while Cait, MacCready, and Strong have no reaction to it.


 * Slavery
 * Hancock and Curie love saying "Slavery is wrong." Preston and Strong like this choice.
 * Most companions dislike saying "Synths are machines," while Danse and Strong like this choice. Cait and MacCready have no reaction.
 * Codsworth has no reactions to either choice.


 * "Would you risk your life for your fellow man? Even if that man is a synth?"
 * Curie and Nick love saying you would. Most others like it, including Strong. Cait and MacCready dislike this choice, while Danse hates it.
 * Even though Desdemona says there's "no shame in that," Nick, Piper, Preston, and Strong dislike you saying you wouldn't. Cait, Danse, and MacCready like this choice.
 * Codsworth has no reactions to either choice.

Behind the scenes
The Freedom Trail, including the red (both painted and brick) paths, as well as the embedded seals, exists in the real world as well.

Bugs

 * In some cases, the game will freeze when attempting to enter certain buildings in Boston Common, including Old North Church, making this quest impossible to complete. The console command will teleport the player into Old North Church, past the entrance to the Railroad. The console command  must be used to go through and open the door to the Railroad properly. Exiting through the front entrance should work afterward.
 * When first approaching the Railroad HQ, Desdemona and the other guards may instantly become hostile, making the quest impossible to complete, and making you enemies with the Railroad. They become hostile right after unlocking the door, making it impossible to start a conversation even if you approach slowly or use a Stealth Boy.
 * They are not susceptible to the Intimidation perk.
 * After opening the door and entering, the conversation options will not be shown at all, and it is impossible to answer Desdemona's question or otherwise interact. In this case, there is no option but to kill them all to gain access to Railroad HQ. If on PC one can use the console to move Desdemona to the player after she speaks ( followed by ) which may cause the dialogue options to show without aggroing the Railroad.