Ten-year-old Grace is in search of a subject for her fifth-grade history project when she learns that her four times-great grandfather once stabbed his lover to death. His grisly act was memorialized in a murder ballad, her aunt tells her, so it must be true. But the lessons of that revelation --- to be careful of men, and desire --- are not just Grace’s to learn. Her family’s tangled past is part of a dark legacy in which the lives of generations of women are affected by the violence immortalized in folksongs like “Knoxville Girl” and “Pretty Polly,” reminding them always to know their place --- or risk the wages of sin.

In November 1944, 18-year-old June Walker boards an unmarked bus, destined for Oak Ridge, Tennessee, which has sprung up in a matter of months. There, June joins hundreds of other young girls operating massive machines whose purpose is never explained. They spend their evenings socializing and flirting with soldiers, scientists and workmen. June longs to know more about their top-secret assignment and begins an affair with Sam Cantor, a young Jewish physicist who oversees the lab where she works and understands the end goal only too well. Across town, African-American construction worker Joe Brewer knows nothing of the government’s plans. But a breach in security will intertwine his fate with June’s search for answers.