In the midst of World War II, hundreds of thousands of British and Allied troops are surrounded by enemy forces on the beaches of Dunkirk, France. Facing imminent danger from the encircling German army and with their backs to the English Channel, the soldiers endure relentless air attacks as they await evacuation. The dire situation prompts the British government to initiate Operation Dynamo, an ambitious rescue plan to bring the stranded servicemen home.

On the home front, civilian efforts augment the Royal Navy’s capacity as private boats are requisitioned to cross the Channel in a risky attempt to save as many lives as possible. The story unfolds through three interwoven perspectives: on land, a young soldier maneuvers through the chaos on the beach, fighting to survive each passing hour; at sea, a civilian mariner and his son, along with a young friend, bravely voyage into the heart of the operation; in the air, a group of Spitfire pilots engage the enemy as they protect the defenseless men below. Their fates intertwine, illustrating the collective struggle to perform a miracle in face of overwhelming adversity.