Agatha's Song

Agatha's Song is a side quest in Fallout 3 as well as an achievement/trophy.

Quick walkthrough

 * 1) Meet Agatha at her house and talk to her about her violin.
 * 2) (Optional) Locate Vault-Tec Headquarters.
 * 3) (Optional) Discover the location of Vault 92.
 * 4) Recover the Soil Stradivarius from Vault 92.
 * 5) Return the violin to Agatha.

Detailed walkthrough
Agatha's house is northeast of Meresti Trainyard and west of the scrapyard, and is surrounded by rock piles except for the small passage from the west over a wooden suspension bridge. The suspension bridge is located just west of where the two sets of upraised monorail tracks become parallel to each other.

Agatha is an elderly violinist who broadcasts her music through her late husband's old radio gear. She wants you to find her great-great-grandmother Hilda's Soil Stradivarius violin, which she believes is still in Vault 92. She offers you the frequency of her radio signal (which plays "beautiful music") as a reward, but with an easy Speech check or a high Charisma, she'll also immediately give you the key to her husband's ammunition box if you promise to get the violin for her. You can also skip the Speech check if you have the Lady Killer perk, and use your wily charms to seduce the woman who appears old enough to be your grandmother. She doesn't know the location of the vault, but if asked can give you the location of Vault-Tec Headquarters on your Pip-Boy 3000. At this point, going to Vault-Tec Headquarters is entirely optional considering you may obtain the location of all vaults in the Capital Wasteland while doing the main quest Picking Up the Trail.

Getting to Vault-Tec Headquarters
To get to Vault-Tec Headquarters, you need to get to Vernon Square. Vault-Tec Headquarters is close to one exit of the Metro Junction tunnels, Vernon Square North.

Once inside Vault-Tec Headquarters, make your way to the Vault-Tec Mainframe. The building is divided into three sections: the guest relations lobby, the corporate offices and the administration. The building is still protected by several automated units such as protectrons, robobrains, turrets, and depending on your level and the game difficulty level sentry bots. There's also a few remaining super mutants when you come in, but they seem to have their hands full.

The mainframe is located in the Administration section. To gain access to it, you will need to obtain permission from System Operation Station 1, 2 and 3. System Operation Station 1 can be found in the room at the top of the stairs that leads to the lower level in the administrations room. System Operation Station 2 can be found in the last room on your left after coming up the stairs leading from the guest relations lobby. System Operation Station 3 can be found in a lower level room (near the door from Administration to Corporate Offices) on a desk next to another terminal. a Alternately if you want to skip most everything in Administration you can also pass by the System Operation Station 3 into the lower floor of the mainframe room, in the Southwest Corner of the room the pipes are laid out in such a way that you can jump onto them then onto one of the server towers (the one with the red lights) under the path to the mainframe. You can simply edge forward while standing on top of one of the server towers until you're touching the Mainframe itself. You can now download the vault locations. Once you gain access to the Mainframe, you'll be able to download the location of Vault 87, Vault 92, Vault 101, Vault 106, and Vault 108 on your Pip-Boy.

If you discover Vault 92 on your own, without having gone to Vault-Tec Headquarters, after accepting the quest, then the optional objective of finding Vault-Tec Headquarters is accomplished, and your new objective is to recover the violin from Vault 92.

Recover the Soil Stradivarius from Vault 92
The entirety of Vault 92 is infested with mirelurks of all kinds. The Soil Stradivarius is located within the most southwestern room in the sound testing section of the Vault on a table.

Entering the vault, go straight; the room should have three doors. The door in front leads to the atrium, the door on the left has signs that say classroom and lab and leads directly to the sound testing section. The door on the right is unmarked and leads to the living quarters. You can move through the vault in at least two ways:
 * If you can pick Average locks, you can go left, directly to the violin, and either ignore the sheet music book or get it after the violin. If you choose this path, enter the door straight ahead, which shortly leads to the sound testing area. Once there, if you're noisy, you'll have several mirelurks on you. On any difficulty, you'll face 2 regular mirelurks and 2 mirelurk hunters. Once you've dealt with the mirelurks, take the corridor on your right. At the intersection, go right around a corner. On your left will be a staircase leading down with a sign saying 'Lab' above it. Be careful, there are 2 mirelurk kings or mirelurk hunters (dependent upon your level).
 * If you cannot pick Average locks, you'll need to go right, through the living quarters, to get the violin. Continue through the living quarters until you are on the upper floor of the atrium. There should be a door to the reactor section, which has a mirelurk hunter, and an unmarked door that leads to the sound testing section. Go through the unmarked door. Once there, immediately to your right should be a staircase with the sign 'Lab' above it leading down.

At the bottom of the staircase and around a corner is a four-way intersection. In front of you is an Average-locked storeroom. To your right is a room with the first mirelurk king (or mirelurk hunter), a juke box, a Nuka-Cola machine and a refrigerator. To your left is a T-intersection. The computer terminal that grants access to the music studio (and the second mirelurk king or mirelurk hunter) is to the left of the T-intersection. The violin is to the right of the T-intersection.

Return to Agatha
After getting the violin, hoof it back to Agatha's house. Upon giving her the violin, Agatha will give you the frequency to her radio channel for your Pip-Boy. It plays violin music and can be heard across the entire wastes.

If you bring Agatha back a sheet music book, which can be found in Vault 92, she will give you the Blackhawk, a unique scoped .44 Magnum and 12 .44 Magnum rounds that was her husband's property. To get the Blackhawk, you must ask for the reward (second option). If you don't have a sheet music book when talking with Agatha again, she'll tell you that she needs music paper to write her music on and asks you to retrieve some for her.

Alternate buyers
You can bring the Soil Stradivarius to Ahzrukhal at The Ninth Circle in Underworld. If you tell him it's one of a kind, he'll buy it off you for 200 caps (or Speech him for 300 caps) and you will get the achievement for finishing the quest. There is no Karma gain nor loss by selling it to Ahzrukhal. (If you don't start Agatha's Song before you give it to him, the game will think that you completed Agatha's Song and you will receive the achievement and in-game recognition of completion.)

It's also possible to sell the violin for 200 caps (300 with speech check) to Abraham Washington in Rivet City. This ends the quest (although you may have never accepted it) and gives you the good Karma bonus. If you talk to Agatha after doing this, you can return to Rivet City and buy the violin, so you can still give it to Agatha when you want to or keep it in your house (since it cannot be dropped until you've completed the quest).

Bugs

 * After talking to Agatha and receiving the quest, but before visiting either Vault-Tec Headquarters or Vault 92 the quest sometimes skips ahead, giving you credit for discovering the location of Vault-Tec Headquarters. This does not seem to affect the quest in any other way.
 * If you find Vault 92 before you find Vault-Tec Headquarters you will receive credit for finding Vault-Tec Headquarters.
 * If you find alternate means of gaining the information contained in the mainframe, or complete the quest without it, then visit Vault-Tec Headquarters, the security door (locked) to the mainframe itself will remain locked with no way to open it, even if you gain access to it using all 3 administration terminals located in the building.
 * After passing the speech check, Agatha will "give" you her ammunition box key, but the box will still be locked and the key won't be on your keyring. You can still open the box, but it has a karma penalty and is considered stealing.