Paris, 1933. Two days before Christmas, the express train to Strasbourg crashes into a local train in the winter darkness outside Paris. On board in Gilles Malroux, a man with a strong reason to avoid the police. In the mayhem of the accident he swaps identity papers with one of the other victims. Giles tries to flee, but, severely injured, finds himself taken to the house of a woman he doesn't know who nurses him. But is the bitter medicine in the spoon she keeps putting to his lips healing him or harming him? Camille Malroux is Gilles's sister. She works for the French Civil Service and is trying to climb the ladder of respectability after a childhood in poverty. When she is informed by the police that her brother is seriously injured in hospital, she rushes to his bedside, to discover it's not Gilles. Only by digging the true identity of the bandaged man in the hospital bed can she hope to trace her brother and save him.