Meggie Elliot is 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. 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. But Meggie suspects Nick of criminal activities, and to expose him would ruin a lot of lives. Against all reason Meggie and Nick begin to fall in love...