Alex was aboard a ship evacuating wounded soldiers before it was attacked by the Germans. He was rescued from the water by Tommy (Fionn Whitehead) and Gibson (Aneurin Barnard), soldiers who were trying to sneak aboard the ship. The three soldiers are taken on another boat the same night. Alex asks Tommy what was up with his friend, while he continued to eat as the rest of the soldiers. However the boat was sunk by a torpedo from a U-boat. Gibson saves Alex and Tommy and the three are taken to shore.
The following day a group of Scottish soldiers inform the three soldiers about a grounded fishing trawler. Alex, Tommy and Gibson follow the other soldiers, as they hide in the boat waiting to evacuate after the tide rises. Soon German soldiers shoot at the boat for target practice, causing the boat to be difficult to keep afloat. Wanting to reduce weight, Alex begins to accuse Gibson of being a German spy, threatening to shoot him. It is revealed to him by Tommy that he is a French soldier who stole the identity of a former English soldier in hopes of evacuating with the British.
The altercation between Alex and Gibson rocks the boat upright, as the engine now starts. The boat is unable to sail very fair before it starts to sink. Alex, Tommy and Gibson begin to abandon the ship, with Gibson drowning in the process.
Alex and Tommy swim for the nearby minesweeper but it was sunk by a German bomber. Mr. Dawson's (Mark Rylance) boat arrives and takes them on board, rescuing them and the other bunch of soldiers from a burning oil slick. They cross the English Channel, seeing the coast of Dorset and are placed on a train. Alex and Tommy expect that their retreat will earn them the scorn of the British public but instead, they receive a hero's welcome. Alex ask a local boy for a newspaper, eventually giving it to Tommy. Tommy reads the We shall fight on the beaches speech to Alex from a newspaper, as Alex continues gazing out of the train window. 
All we did is survive.
—Alex to the Blind Man
You don't speak English and if he does it's with an accent thicker than sauerkraut sauce.
—Alex talking about Gibson