An orphan coming of age without a penny to her name, Marion joins the Women’s Royal Navy Service (the “Wrens”) as a motorcycle despatch rider on the Western Front, assigned to train and deliver carrier pigeons to the front line. Despite the hardships and constant threat of danger, Marion feels as if she finally belongs and that she has a purpose. Meanwhile, she and her childhood best friend, Eddie, dream of a future after the war—until tragedy strikes. A society girl, Evelyn has overcome a childhood disability and has found her true passion in automobile racing. When England enters WWII, Evelyn sees an opportunity to use her skills as a despatch rider, but her parents threaten to cut her off if she doesn’t start acting like a lady and marry the man they have chosen for her. Meanwhile, a fellow Wren shows up at Marion’s door with an unwelcome call to return to her service.