Similar to previous Fallout games, Fallout 3 takes place in post-apocalyptic United States. For 200 years, Vault 101 has faithfully served the surviving residents of Washington DC and its environs, now known as the Capital Wasteland.
Though the global atomic war of 2077 left the US all but destroyed, the residents of Vault 101 enjoy a life free from the constant stress of the outside world. Giant Insects, Raiders, Slavers, and yes, even Super Mutants are all no match for superior Vault-Tec engineering.
Yet one fateful morning, you awake to find that your father has defied the Overseer and left the comfort and security afforded by Vault 101 for reasons unknown. Leaving the only home you’ve ever known, you emerge from the Vault into the harsh Wasteland sun to search for your father, and the truth.