Belgium May 1940. German forces invade the Low Countries; untried units of the British Expeditionary Force are poised to repel the German advance. Bombardier Alan Hibbert and his gun crew see action for the first time when they fight rear guard actions during the BEF withdrawal, until they receive their order to retreat. They witness the carnage that is Dunkirk, deciding to make their own way across the channel. Returned to camp they start to adjust to everyday life when an unexpected twist of fate sees them suddenly returned to France. But this time it's behind enemy lines....