1944. When sixteen-year-old Ruby Pickett and her family move to the new, government-built city of Oak Ridge, Tennessee, Ruby knows that her daddy's new job will help the war effort, but she has no idea how. Ruby is not alone in her lack of knowledge, as the city's true purpose is a carefully guarded secret. A thinker and a reader, Ruby has always been restless, and she finds Oak Ridge a much more stimulating environment than her old home in rural Southeastern Kentucky.

Ruby finds a kindred spirit in twenty-three-year-old Iris, a wife and mother who has moved to Oak Ridge with her scientist husband and is frustrated by the intellectual limitations of being a full-time housewife. Ruby and Iris's relationship starts as friendship but deepens in emotional intensity until it, like the purpose of Oak Ridge itself, is a dangerous secret.