In the year 2077 of an alternate history Earth where people never quite got over the '50s- the world is plunged into nuclear armaggeddon, the fallout of which - 100 years later - has given rise to a rag-tag society mainly comprised of steampunk enthusiasts.
Before the bombs fell, however, the US government built a series of fallout shelters called "Vaults" - ostensibly to protect the populace but with a hidden agenda to subject their occupants to cruel and unusual social and environmental experiments.
As part of one of these tests - the computer chip maintaining the water supply in Vault 13 fails - and the stricken vault dwellers must pin their hopes on you, a young hero to venture into the wasteland and save them.
But the story does not end there - a hundred years on, another young vault dweller sets out into the ruins of Washington DC, shouldering the enormous task of providing clean water for everyone in the wasteland. Meanwhile, on the opposite coast, a young courier in the Mojave desert, a young courier is shot in the head over a mysterious platinum chip, but is lucky to survive and seeks revenge.
Pick up your weapon of choice be it machete, revolver, or laser gun and get out there.