Tending to the soldiers in the trenches of France during the First World War, battlefield nurse Bess Crawford is sent back to England in the early summer of 1917 with a convoy of severely burned men. One of her patients, a young pilot, has clung to a photograph of his wife since his plane went down, and Bess can't help but notice the photo every time she tends to him. After the patients are transferred to a clinic in Hampshire, Bess is ready for her two-day leave, planning to return to her flat in London to catch up on some much-needed rest. But at the railway station, in a mob of troops leaving for the front, Bess catches a glimpse of a familiar face. Could that be the pilot's wife? And why is she bidding a very emotional farewell to a soldier who is not her husband? Back in France, Bess discovers an old newspaper with a drawing of the woman's face on the front page. Accompanying the drawing is a plea from Scotland Yard looking for information from anyone who has seen her. The woman was murdered - the very day Bess saw her...