Set in 1912 during the growth of American exceptionalism, the game has protagonist, former Pinkerton agent Booker DeWitt, sent to the floating air-city of Columbia to find a young woman, Elizabeth, who has been held captive there for most of her life. Though Booker rescues Elizabeth, the two are pursued by the city's warring factions: the nativist and elite Founders that strive to keep the city for pure Americans, and the Vox Populi, a rebel grouping representing the common people. Booker finds Elizabeth to be central to this conflict, and learns that she possesses strange powers to manipulate rifts in the time-space continuum that ravage Columbia.