May 1940. Sergeant Jack Tanner has been posted to a training company on the south-east coast of England. But all is not well in the camp. The mysterious death of two Polish refugees leads Tanner to believe there has been foul play. When he and his corporal, Stan Sykes, are nearly killed, Tanner finds his suspicions directed at an old comrade from his early days in the army. As the Germans launch their Blitzkrieg in Europe, training is abandoned and the entire company are sent to join the battle to stop Hitler's drive across the Low Countries. Almost immediately, they are thrust into the thick of the action and cut off from the rest of the battalion. Trapped behind the enemy advance, Tanner must use all his ingenuity to get his men back to Allied lines. Soon enmeshed in the long withdrawal to the French coast, Tanner, Sykes and his new platoon commander, Lieutenant John Peploe, find themselves pitted against not only the die-hard Nazis of the SS 'Death's Head' Division but also the great panzer commander himself, General Rommel. Even then, in the chaos of retreat, Tanner must deal with the corrosive treachery bubbling within the company's ranks - and an enemy more deadly than the Germans - if he and his men are to have any hope of surviving the mayhem of Dunkirk.