It is early May: the year 1940. In London, the civil population, lulled into an atmosphere of false security, goes about its business as usual. Even the official war communiqués merely report activity on the Front. But Charles Forman, war correspondent, knows better. As the war in France takes a turn for the worse, he signs on with the Merchant Navy and volunteers for the greatest mission ever mounted ... the evacuation of Dunkirk.