Boulder City Showdown

 is a quest in Fallout: New Vegas.

Overview
Jessup is holding NCR troops hostage in the Boulder City Ruins.

Objectives

 * Meet with Jessup, leader of the Great Khans in Boulder City

Option: Negotiate

 * Negotiate for the release of the NCR hostages
 * Return to Lt. Monroe and inform him that you've worked out a deal with the Great Khans

Quick walkthrough

 * Speak to Monroe in Boulder City to begin the quest

Option: Free Hostages via Negotiation

 * Meet with Jessup, leader of the Great Khans in Boulder City.
 * By passing a speech check (45), the player can convince Jessup to have the Khans to go peacefully.
 * Return to Lt. Monroe and speak to him.

Option: Free Hostages by Killing the Khans

 * Kill all of the Great Khans standing guard.
 * Enter the building Jessup is in (find the door near the building the hostages are in) and kill the 2 remaining Khans.
 * Release the hostages.
 * Return to Lt. Monroe and speak to him.

Option: Killing the NCR Troops

 * The player must kill all the NCR troops in the area, including Lieutenant Monroe.
 * Once all NCR soldiers are dead, inform Jessup.

Detailed walkthrough

 * Speak to Lieutenant Monroe to begin the quest, and walk through the door behind him. From here, the player has 3 options as to how to proceed:

Option: Free Hostages via Negotiation

 * Enter the Boulder City Ruins and go into the Great Khans hideout.
 * Talk to Jessup.
 * By passing a speech check (45), the player can convince Jessup to release the hostages and have the Khans to go peacefully
 * The player can convince Jessup to shoot his way out
 * The player can convince Jessup to release the hostages
 * By asking Jessup about the Platinum chip, the player will complete They Went That-a-Way
 * Go back and speak with Lieutenant Monroe. He informs the player he's been given orders to kill the Great Khans, hostages or not.
 * The player can talk Monroe into honoring the deal and not killing the Great Khans. This results in the player gaining fame with the Great Khans and the NCR, and an additional 400XP.
 * The player can offer to give him 500 caps (or less, with 45 barter) to let the Khans escape.

Note: If the player engages in hostile action with the Great Khans, the player will still be accepted with both factions.

Option: Free Hostages by Killing the Khans

 * The player may choose to free the hostages by killing all the Khans in the area.
 * The player must kill all the Khans in the Ruins, including the two in the Hideout.
 * Release the two NCR hostages in the building next to the Hideout.
 * Return to Lt. Monroe and speak to him.
 * Upon completion, the player will gain fame with the NCR and infamy with the Great Khans.

Option: Killing the NCR Troops

 * The player must kill all the NCR troops in the area, including Lieutenant Monroe. There are about 5 soldiers when you enter the ruins.
 * Once all NCR soldiers are dead, inform Jessup the Khans are free to go.
 * Note: The hostages will remain tied up in the ruins. The player can either leave them be, free them or kill them. Killing them results in XP and NCR infamy. The Great Khans will attack the player if the hostages are engaged, so wait for them to leave the area.
 * Upon completion, the player will gain fame with the Great Khans.

Notable Loot

 * True Police Stories
 * La Fantoma
 * Jessup's Bandana on Jessup.

Video Walkthrough
http://www.youtube.com/watch?v=IcSY945zrGM

Bugs
If you go to New Vegas and circumvent the entire Boulder City main-quest arc, Jessup's only dialog response will be to say Goodbye, making the quest impossible by diplomatic means.

Sometimes if you provoke a firefight between the NCR and the Khans and kill them all, the lieutenant will keep saying "Can't talk now--we haven't gotten all the Great Khans".