故事素材来源于二战中的真实事件，也就是众所周之的“敦刻尔克大撤退”。二战初期，德军把40万英法盟军围困在了敦刻尔克的海滩上，准备将其一网打尽，面对危机，英国政府和海军启动了应急方案，发动大批船员和民众展开了营救军队的行动

民用船主道森先生（马克·里朗斯饰）响应英国政府的号召，带领儿子彼得和17岁少年乔治踏上了前往敦刻尔克拯救士兵的征程，与此同时，英国士兵汤米（菲昂·怀特海德饰）与吉布森和亚历克斯一起开始了逃亡生涯。

道森一行人到达敦刻尔克后就开始工作，他们先后搭救了飞行员柯林斯、海军（基里安·墨菲饰），还有汤米等人。飞行员法瑞尔（汤姆·哈迪饰）面对敌人两面夹击而英勇战斗，相继击落多架敌机。影片从陆、海、空三个角度来讲述这场大撤退的艰难程度，人们不得不为生存而战斗。

The story material comes from real events in World War II, which is the well-known "Dunkirk retreat". In the early days of World War II, the German army besieged 400,000 British and French allied forces on the beaches of Dunkirk, preparing to wipe them all out. Facing the crisis, the British government and navy launched an emergency plan, mobilizing a large number of crew and people to rescue the army.

Mr. Dawson (Mark Rylance), the owner of the civilian ship, responded to the call of the British government and led his son Peter and 17-year-old George Embarked on the journey to Dunkirk to rescue the soldiers, at the same time, the British soldier Tommy (Fionn Whitehead) started his escape career with Gibson and Alex.

Dawson and his team started working after arriving in Dunkirk. They successively rescued the pilot Collins, the navy (Killian Murphy), Tommy and others. Pilot Farrell (played by Tom Hardy) fought bravely in the face of the enemy's attack from both sides, and shot down many enemy planes one after another. The film tells about the difficulty of this great retreat from three perspectives: land, sea, and air. People had to fight for survival.