Trigger the Gala Event

Trigger the Gala Event is a quest in the Fallout: New Vegas add-on Dead Money.

Detailed walkthrough
Father Elijah will tell the Courier the only way to gain access to the casino is to "Trigger the Gala Event." This requires them to escort their three companions to three specific spots located around the Sierra Madre during their respective quests: Fires in the Sky, Strike Up the Band, and Mixed Signals.

The quest will then start and will mark the bell tower where one must enter Salida del Sol and make their way through numerous ghost people to get to the courtyard, from there one must follow a narrow route to the top of the tower. There will be a console by a window facing the casino, once activated, it will result in an achievement: Having a Ball, 100 XP and the casino will come to life with fireworks, music, and lights. But it also gets the attention of the ghost people, which flood into the area below. In the bell tower one can find the vending machine password for super stimpak and for the holorifle focus optics mod.

The player character must fight (or run) back the way they came, to the central fountain in the villa, before entering the casino by the gate just behind it. One can simply run past the ghost people, as they will not follow into the next section. Leaving Salida del Sol after Trigger the Gala Event is made easier by the graffiti on the walls: numerous tags saying things like "Run, run, run!" are spread along the route out of this area. Before leaving this section of Salida del Sol, there is a room with a Dean's secret stash, several desks (with ammo and chips inside each) stacked on edge, and the Snow Globe - Sierra Madre (in the corner, on top of a crate). One can find this room by running along the outside awnings (one level above street level) and going through a hole in the wall. It is near the gate that requires a key to exit the area.

Upon activating the gala event, some new speakers will activate (especially the red speaker, which is indestructible) making it difficult to exit Salida del Sol North the same way one came in. One can alternatively exit through the gate in the southwestern corner, just north of the entrance into Salida del Sol. The player character will have to drop down from the rooftops into a courtyard filled with the Cloud.

Behind the scenes
The music playing at the hotel when the Gala Event is triggered is "American Swing."

Bugs

 * If the player visits the bell tower before they have completed the three quests leading up to this one, it will automatically be triggered. This trigger is not complete, however, as no enemies are added, no fireworks displayed and the door to the casino may stay locked, or it may be open with all companions (including ones whose quests have not been completed) already in the casino.
 * During the quest "Trigger the Gala Event," when approaching the control panel in the bell tower to activate the gala event, a scripting error may occur, which causes nothing to happen when activating the control panel which leaves the player unable to finish the quest leaving them stranded at the Sierra Madre.
 * This can be fixed by reloading a save before entering the last floor of the bell tower.
 * This can be worked around by proceeding back to the fountain and typing CompleteAllObjectives xx000fc0 (this will close the quest) and unlock 01001314, which will open the gate and let the player go through.
 * During the end of the quest when the player has to activate the trigger, the game shows nothing to activate it leaving the player stranded.
 * Sometimes, once activating the panel in the bell tower, the fireworks may not appear.
 * Sometimes after completing the last follower quest (Dog/God, Christine, Dean Domino) the quest will not appear which keeps you from opening the gate to the courtyard. Reload to a save before completing the last of the three follower quests to fix this.