France in May and June of 1940: the French and British armies are trapped by the advancing German troops at town of Dunkirk. Their only chance is to be evacuated across the English channel. The easygoing British Corporal Binns, who so far has resisted any increase in rank, finds himself responsible for the lives of his men when their officer is killed. He and his men have become detached from the rest of the retreating Allies. He organizes the lost troop and sheppards them back to Dunkirk. Meanwhile, British civilians are being dragged into the war with Operation Dynamo, the scheme to get the French and British forces back from the Dunkirk beaches. Some come forward to help, others are less willing.