Meggie Elliot is a young woman of above average intelligence, and on the brink of adulthood. Living with her aunt and uncle in London at the outbreak of World War II she's intent on going to university, then pursuing a career in law. She is encouraged in this by her solicitor -- a man she admires a little too much. Too old for her, he lets her know it. Meggie follows her dream as best she can, knowing it's unlikely it will ever come to fruition. In a burst of patriotism she joins the WRNS to do her bit for the war effort. Sent to work in a decoding unit she meets the dangerously exhilarating young aristocrat, Nicholas Cowan, who sweeps her off her feet.