Disguised as her late brother Cooper in the 19th Massachusetts Volunteers, Catherine Samson fights to quell the Confederate rebellion and preserve her nation's unity. She believes the Constitution's declarations of equality and freedom apply to everyone, and dreams that someday they will extend to her own pursuit of happiness with a woman.

Helping her father raise her siblings on their Gettysburg farm, Sophie Bauer likewise clings to hope for a woman to love, but when she serves as an army aide and meets Cooper, Sophie is confounded by her growing feelings for him. Catherine, meanwhile, wrestles with her deception and the disguise she must maintain. Disclosure could not only repulse Sophie but send Catherine home a social outcast.

When the battle of Gettysburg engulfs the Bauer farm, Catherine and Sophie learn far more about themselves than they ever expected. But first there's a war-and hearts-to be won.