Orphan Marion Hoxton joined the Women's Royal Naval Service—the Wrens—during the Great War, gaining sisters and a sense of purpose. She and her childhood friend Eddie dream of a future together—until the battle that changed everything. Two decades later, another war has broken out, calling Marion to return to the fight. Hoping to forget her traumatic childhood, 20 year old society girl Evelyn Fairchild also signs up. The Wrens are ready for action, but this war will bring unimaginable challenges to these stalwart women.