Lady Elizabeth Neville-Ashford wants to travel the world, pursue a career, and marry for love. But in 1914, the stifling restrictions of aristocratic British society and her mother’s rigid expectations forbid Lilly from following her heart. When war breaks out, the spirited young woman seizes her chance for independence. Defying her parents, she moves to London and eventually becomes an ambulance driver in the newly formed Women's Army Auxiliary Corps—an exciting and treacherous job that takes her close to the Western Front.

Assigned to a field hospital in France, Lilly is reunited with Robert Fraser, her dear brother Edward’s best friend. The handsome Scottish surgeon has always encouraged Lilly's dreams. She doesn't care that Robbie grew up in poverty—she yearns for their friendly affection to become something more. Lilly is the most beautiful—and forbidden—woman Robbie has ever known. Fearful for her life, he's determined to keep her safe, even if it means breaking her heart.

In a world divided by class and filled with uncertainty and death, can their hope for love survive...or will it become another casualty of this tragic war?