Quick walkthrough
- Travel to Rivet City and enter its science lab.
- Find and talk to Dr. Madison Li.
- Go to the Jefferson Memorial and find Dad's holotapes.
- Travel to Vault 112 and enter the Tranquility Lane lounger.
 Detail walkthrough
 Rivet City and Dr. Li
Rivet City is a massive (now defunct) aircraft carrier docked in the far southeast of the Capital Wasteland. It can be traveled to by land and follwoing the Potomac River or by slipping down into a metro tunnel and emerging from the nearby Anacostia Crossing metro.
In the science lab of Rivet City, Dr. Li knows your father, James. She offers details on his old project and tells you where James ran off to: the Jefferson Memorial. If you've been to this location and visited the underground tunnel, the game will allow you to tell her that he isn't there; she will instead insist that you go back as his notes were left there.
 Project Purity's control room
The memorial is now infested with super mutants which patrol the catwalks outside and the interior. Enter the memorial through the metal door labeled Gift Shop; it's on the right front side with a metal frame around it and a set of lights next to it. Make your way to the Rotunda by following the signs.
Once in the Rotunda, walk up to the auxiliary filtration unit near the entry way and pick up the Project Purity journals resting here. One of the tapes, tape #10, will indicate that your father has left for Vault 112 already. The location will be added to your map; there are several other points of interest in the area, which makes it relatively simple to fast travel to.
 Gain access to Vault 112
Walk or fast travel to Smith Casey's Garage. Once inside, progress past the front desk and into the back room, killing the radroaches and mole rats inside. You will find a switch located on the wall to your left that operates a large hole in the floor. Activate the switch and the door will open. Proceed down the stairway, down the next set of stairs and to the bottom. You cannot miss the massive Vault 112 doorway. Activate the door using the panel and you can walk in. Next walk down into the Tranquility Lane lab and find the only unoccupied operational tranquility lounger. Entering it completes the quest.
- Smith Casey's garage can be accessed straight after the player leaves Vault 101, therefore advancing through a large section of the game's main quest-line.