Picking up the Trail

Picking up the Trail is a main quest in Fallout 3 as well as an achievement/trophy.

Synopsis
James determined that a Garden of Eden Creation Kit would be needed to ensure the success of Project Purity; to this end, the Lone Wanderer must find a way into Vault 87 – the only vault in the region to have such an extraordinary device.

Walkthrough

 * 1) Talk to Head Scribe Rothchild about the location of a GECK.
 * 2) Look at the vault listings in the Citadel science lab.
 * 3) Gain access to Little Lamplight.
 * 4) Mayor MacCready will only allow the Lone Wanderer entrance after succeeding a Speech check or having the Child at Heart perk. Failing that, one must complete Rescue from Paradise to gain access.
 * 5) Gain access to Vault 87 by going through Murder Pass. Alternatively, speak to Joseph and ask him to restore power to a computer terminal in the Great Chamber; hacking the terminal (Science of 50 required) will allow one to enter Vault 87 directly, and bypass Murder Pass.

Bugs

 * In some instances Rothchild will tell you to follow him then make no effort to move, even under duress. To fix this just reload and approach Rothchild at a different time of the day — preferably when a non-player character is talking to him and his back is turned — then begin the dialogue again. Another options are to push him until he is near the wall directly on the left of the door leading to the Mess Hall, or to drag Rothchild's body to the desired location by knocking him unconscious, or to disable then re-enable him using the console.
 * Scribe Rothchild may disappear from the Citadel, preventing the player from being briefed and advancing the quest. This can be fixed on PC by using the console command . For non-PC quest advancement you must load a previous save file and attempt to relocate Scribe Rothchild within the Citadel to receive your next objective.
 * Sometimes Scribe Rothchild will disappear after you read the Vault-Tec computer. Your quest will tell you to talk to him but the quest marker will point to a location on the world map in middle of nowhere. Loading a previous save file and restarting the quest can correct the misplaced quest marker, and direct you to Scribe Rothchild for your next objective.
 * Talking to Rothchild when he is in the A Wing instead of the Laboratory may result in a bugged and broken quest. Making him unconscious by shooting him can sometimes fix this.