"A moving tale of female solidarity and courage." --Kate Quinn, New York Times bestselling author of The Alice Network

December 1917. As World War I rages in Europe, twenty-four-year-old Ruby Wagner, the jewel in a prominent Philadelphia family, prepares for her upcoming wedding to a society scion. Like her life so far, it's all been carefully arranged. But when her beloved older brother is killed in combat, Ruby follows her heart and answers the Army Signal Corps' call for women operators to help overseas.

As one of the trailblazing "Hello Girls" deployed to war-torn France, Ruby must find her place in the military strata, fight for authority and respect among the Allied soldiers, and work to secure a victory for the cause. But balancing service to country is complicated further by a burgeoning relationship with army medic Andrew Carrigan.

What begins as a friendship forged on the front lines soon blossoms into something more, forcing Ruby to choose between the conventions of a well-ordered life back home, and the risk of an unknown future.