Underground Undercover

Underground Undercover is a quest and achievement/trophy in Fallout 4.

Quick walkthrough
Infiltrate The Institute and meet with The Patriot.

Detailed walkthrough
The quest begins with the choice of killing Desdemona.

Bugs

 * It is possible that Desdemona will not initiate dialogue when trying to warn her about the brotherhood.
 * This may be caused by Glory being dead. To fix go to Railroad HQ and use recycleactor 000508EE and 000508EE.moveto player in the console. This must be done before Z1-14 informs the Sole Survivor of the impending Brotherhood attack.
 * It is possible that during and after Glory assists the player during the quest Memory Interrupted she can either become stuck in the area or die, resulting in a halt to progress for Underground Undercover. This is because Glory is involved in a dialogue with the player during the Brotherhood of Steel warning event. To avoid this, the player should follow Glory out of the Malden Center Station as she can become stuck on metro gates or other objects.
 * The quest can be force completed by using either the command setstage rr201 1100 or completequest rr201 at the Railroad HQ, however this will not initiate the next quest, Precipice of War. This method is only effective if a way to force start the next quest is available.
 * This may be caused by Brotherhood important NPCs being dead. To fix use recycleactor in the console for every dead body left on Prydwen, Boston airport and Cambridge Police Station. It is uncertain though who exactly causes this. This must be done before Z1-14 informs the Sole Survivor of the impending Brotherhood attack.
 * Try to load any save that the Sole Survivor didn't kill any Brotherhood of Steel in their base (The Prydwen, Boston Airport and Cambridge Police Station)
 * This bug can also occur if the player character has not killed any members of the Brotherhood of Steel in The Prydwen, Boston Airport, or the Cambridge Police Station, or if Glory is still alive.
 * Sometimes the 'Continue Working With Father' objective never ends, even past Mass Fusion and Powering Up. Can use the console command 'setstage 00b2d48 910' to move past this glitch. Talking to Liam Binet could also trigger a runner to come get you on Z1-14's behalf.
 * Sometimes the Encrypted Message Holotape will not be added to your inventory. A console fix for this is: "player.additem 0020b00e 1"
 * Should Tinker Tom get downed in combat with other NPCs prior to the player securing the Vertibird, a bug is present where Tom will still be incapacitated by the entrance door to each new area the player spawns into. The player will not be able to revive him with a stimpak, and as such he will not be able to fly the Vertibird, effectively bringing the quest to a complete halt.
 * When prompted to kill the tunnel guards. Only 4 of the 5 guards spawn. This causes a the 5th guard marker to spawn underneath the floor.

Tapadera subterránea