Agatha's Song

 is a Fallout 3 quest. It is also an Xbox 360 and PC achievement.

Walkthrough
Agatha is an old woman living alone in a house in the Capital Wasteland. Her house is west of the Scrapyard and can be tricky to find since it is surrounded by rock piles except for the small passage from the west. If you are having troubles finding it, then look for caravans in the area with your V.A.T.S. since they are often positioned right in front of the passage to her house.

Agatha is a talented violin player who broadcasts her music through her late husband's old radio gear. She wants the Vault 101 dweller to find music paper for her, as well as her great-great-grandmother Hilda's Soil Stradivarius violin, which she believes is still in Vault 92. (Optional) You can visit Vault-Tec's Headquarters to get the location and passcodes for Vault 92.

Vault 92 itself is infested with Mirelurks, Mirelurk Hunters, Mirelurk Kings, Bloatfly, and Radroach. The Vault is decently easy to navigate, so long as you follow the signs, you can explore the Vault to find various items including bullets, parts to assemble weapons, and varies drugs and aid items. To get the Soil Stradivarius, the easiest way is, once you enter the vault go through the door straight ahead of you, follow the corridor until you get to the open room with the Bloatfly, take the left most doorway and follow that corridor until you find the Mirelurk Hunters, there will be 2 in this area. You'll have to find a switch to open the studio room, which you will have to fight both Mirelurk Hunters to get to, once you find the switch, go into the studio to get the Soil Stradivarius and take it to Agatha, she rewards you with the frequency to her radio station. It's possible to sell the violin for caps to Abraham Washington in Rivet City, or to a ghoul in Underworld.

To sum it up: Follow the signs for the LAB. The area where the LAB can be found is called the "Sound testing" Area. In that area there will be a staircase leading down. There are two Mirelurk Kings down there, so be careful, quiet (to snipe them in the head!), or both. Once down the staircase and around some corners, you'll come to a 3-way intersection with a locked door straight ahead and one of the Mirelurk Kings in a room to your right (has a juke box and soda machine in it). Once you've dealt with him, turn around, pass the locked door on your right, and you will come to a T-intersection. Go left, around a corner and into a room with the other Mirelurk Kings. Dispatch him, access the computer to unlock the music room (which you can see through the windows). The Strad is in that room on the table by the window.

If you use the "Noise Flush" command on one of the security terminals (three located in Living Quarters: one by the door to male and female dorms and a separate one in one of the rooms), it will kill all the Mirelurks in the Living Quarters.

Sheet music can be found in the Male Dorm bathroom, in the last stall, in Vault 92. Another piece of sheet music is also located on the floor of the Arlington Public Library in the children's department. There is also a copy in Springvale Elementary, located behind an overturned desk. If you bring Agatha back either piece of sheet music, she will also give you the Blackhawk, a modified .44 Scoped Magnum that was her husband's property.

Upon completion of this quest you also have Agatha's radio station added to your Pip boy. It plays violin music and can be heard across the entire wastes.

Alternatively, you can also bring the Soil Stradivarius to Ahzrukhal in The Ninth Circle in the ghoul town of Underworld. If you tell him it's one of a kind, he'll buy it off you for a few hundred caps and you will get the achievement for finishing the quest.