Underground Undercover Main Story, The Railroad Quest
Talk to Desdemona in Railroad HQ after visiting The Institute.
This quest will be triggered or can be aquired when you complete The Molecular Level quest.
Related points of interest
Stages of "Underground Undercover" quest
1. Talk to Desdemona
Desdemona will tell you about Patriot, a man or woman inside the Institute who helps synths escape to freedom.
3. Upload encrypted message on any Institute terminal
Desdemona gave me an encoded holotape that I can use at any Institute terminal to make contact with the Railroad's guardian angel, Patriot. Perhaps with him (or her) we can devise a way to rescue many synths.
You can use any terminal in the Institute, i.e. the terminal close to the portal you used during your first visit in The Institute, etc.
Load Encrypted Message Holotape and select Copy encrypted message.
5. Meet Patriot
Tinker Tom's encoded holotape worked. I sent an encrypted message to Patriot and received a message back: "Meet at the Advanced Systems maintenance room."
6. Follow Liam
I've met Patriot, Liam Binet. He's eager to rescue a lot of Synths at once. But in order to do that we'll need help. I should follow Liam to meet his accomplice.
8. Talk to Desdemona
Patriot has a plan to rescue 13 Synths at once. But he needs login credentials for CIT's original security system, Code Defender, to do so. I should contact Desdemona to find them.
Desdemona will tell you that you should write up a full report on PAM's terminal.
11. Get password for Code Defender
A man named Wilfred Berman worked at Cambridge Polymer Labs. PAM says he would've had the login credentials we need to rescue Patriot's 13 Synths. Now it's just a matter of finding them.
Find Bergman's Terminal and use Password request (Archive) option. Check Cambridge Polymer Labs quest description for more details.
12. Return to Desdemona
Now that I have the login credentials for Code Defender, I need to contact Desdemona. Hopefully she's come up with a plan to help rescue Patriot's 13 Synths.
13. Meet with Z1-14
Desdemona doesn't want to rescue 13 Synths. She wants to rescue them all. So I need to give Patriot his login credentials. But more importantly I should see if Z1-14 is willing to fight for his freedom.
15. Give Z1-14 a day
Z1-14 is willing to fight for his freedom, but he needs 24 hours to contact other potential Synth rebels.
You can use one of the benches located in the central part of the Institute and wait 24h.
16. Meet with Z1-14
17. Kill the tunnel guards
Z1-14 found many volunteers willing to fight for their freedom. But they need weapons. There's a mining tunnel that has materials they need to make crude weapons. I just have to take out the guards.
18. Return to Z1-14
With the tunnel guards eliminated, Z1-14 has the materials he needs to make crude weapons for the uprising. Now I need to let him know the good news.
19. Continue working with Father
Z1-14 will need time to build weapons and recruit more rebels. Until then I need to continue working with Father in order to maintain my cover. When the time is right, Z1-14 will contact me.
You have to complete Powering Up quest.
20. Meet with Z1-14
I've received a cryptic message from Z1-14. He wants to meet. Perhaps he's finally ready to launch the Synth rebellion.
21. Warn Desdemona
Z1-14 has urgent news. The Brotherhood of Steel has somehow discovered the location of Railroad HQ. I must warn Desdemona before it's too late.
22. Quest completed
Z1-14 and his rebel Synths are armed and ready. Now I just need to save the Railroad then teleport my friends inside the Institute.
Next / new quest is Precipice of War (Main Story, The Railroad).