In 1918 Lily Deacon is surprised to be asked to join a commission investigating the morals of young Englishwomen serving at the Western front in the First World War, an interruption to her ordered life and her work as a factory inspector. Whilst in France, by chance she hears the reminiscences of a wounded soldier and promises to try and find out what happened to the young doctor Edward Hamilton and nurse Lucy Smith, who saved his life on their voyage to South Africa in 1900. Within a matter of weeks she has fallen in love with an army surgeon, become a courier for secret information and uncovered the full story of what happened to Lucy and Edward all those years ago. She suspects her life will never be quite the same again...