Plot and Story. FALLOUT 3 
Fallout 3 takes place in a post-apocalyptic, retro-futurist Washington D.C. and parts of Maryland and Virginia in the year 2277 after a world war over resources which ended in nuclear holocaust in 2077. The player character (PC) lives with their widower father, James (voiced by Liam Neeson), in Vault 101 (one of several fallout shelters in the D.C. area). One day, the PC wakes up to find that James has left the Vault and ventured into the Capital Wasteland - as the area around D.C. is now known - for unknown reasons. The Vault Overseer becomes suspicious and orders his men to kill the PC, forcing the player to go out into the Capital Wasteland where they must follow James' trail and learn why he left.Along the way, the player will encounter various factions, including the Brotherhood of Steel, a group of technology-coveting survivors from the American West Coast, the Outcasts, a group of Brotherhood of Steel exiles, and the Enclave, the elitist and genocidal last remnants of the U.S. government.
Story
The main quest begins after the Lone Wanderer (the title given to the player character by the populace of the Capital Wasteland) escapes Vault 101 at age 19. The search for James, the player's father, takes the character on a journey through the wasteland, first to the nearby town of Megaton, named for the undetonated atomic bomb at its center, then the Galaxy News Radio station. The player then travels to Rivet City, a derelict aircraft carrier now serving as a human settlement. Here the player meets Doctor Li, a scientist who worked alongside the player's father. Doctor Li tells the player of Project Purity, a plan to remove the radiation from the water of the Tidal Basin, as a means of restoring the environment and improving the lives of those inhabiting the wasteland.
After investigating the former lab of Project Purity, built inside the Jefferson Memorial rotunda, the player tracks James to Vault 112, and frees him from a virtual reality program being run by the Vault's corrupt Overseer. The player and James return to Rivet City and meet up with Doctor Li. They discuss the Garden of Eden Creation Kit (G.E.C.K.) and its possible whereabouts, which are rumoured to be in Project Purity's computer database. However, while the player helps James restart the lab equipment, the Enclave (the post-Great War United States government) arrives and attempts to take over the project for their own purposes. During a confrontation, James sacrifices himself and kills several Enclave soldiers by overloading Project Purity's main chamber with lethal amounts of radiation. After fleeing the lab through underground tunnels, Li and the player arrive at the Citadel of the Brotherhood of Steel, which is in the ruins of the Pentagon. After recovering, Li pleads with the player to find a G.E.C.K. to finish James' work. The player eventually finds one in Vault 87, which had been dedicated to creating and perfecting the FEV (Forced Evolutionary Virus). After retrieving the G.E.C.K., the player is ambushed once more by the Enclave, who take the player captive.
Awakening in a holding cell in the Enclave base at Raven Rock, the player is briefly interrogated by Colonel Autumn and then summoned to the office of President John Henry Eden, who promises safe passage to his control room. While the player is en route, however, Colonel Autumn, acting against Eden, orders the Enclave soldiers to attack, and the player must fight their way to the control room. There, Eden, who turns out to be a supercomputer given control of the East Coast of the United States, gives the player a modified form of the FEV virus, which will kill all individuals with any level of mutation (i.e., everyone), and requests that the player insert it into Project Purity.
The player escapes Raven Rock (which will be destroyed shortly thereafter if the player convinces Eden to trigger a self-destruct) and returns to the Citadel, where Elder Lyons (leader of the East Coast branch of the Brotherhood of Steel) will ask the player for any information they have. The Brotherhood of Steel also enlists the player's aid in assaulting the Jefferson Memorial with Sarah Lyons, the leader of an elite squad of Brotherhood Knights, and a gigantic pre-war robot built to liberate Alaska named Liberty Prime. After breaking through to Project Purity, the player must deal with Colonel Autumn through violence or persuasion. Through the building's intercom, Doctor Li informs the player that due to the damage caused by the recent fight, someone must activate the system before it overloads, destroying the facility. Unfortunately, the one who activates the system will have to be sacrificed due to the chamber being close to overwhelmed by lethal amounts of radiation. In the end, the choice comes down to the player, who must choose whether to activate the system personally, convince Sarah Lyons to do it, or simply wait, which ends in the facility's destruction. If the Broken Steel DLC is installed, the player also has the option of having one of three radiation resistant followers (a Super Mutant, a Ghoul, or a robot) activate it, should one of those three have been recruited and brought along. The ending sequence that follows depends on the player's actions in the game, karma, who activated the purifier, and whether or not the player tainted the water with the modified FEV virus.
