In the early hours of June 6, 1944, Allied forces prepare for the most ambitious amphibious military operation in history, targeting the heavily fortified coast of Normandy, France. The film meticulously weaves together the perspectives of American, British, French, and German soldiers, as well as civilians, to portray the immense scale and complexity of the D-Day invasion. Various commanders grapple with the immense logistical challenges, crucial decision-making, and unpredictable weather, while troops embark on perilous landings under a relentless barrage of enemy fire. Intelligence officers and resistance fighters also play pivotal roles, attempting to sabotage German defenses and gather critical information.

The narrative intricately showcases the chaos and valor on the beaches, in the air, and in the towns, reflecting personal stories of bravery, sacrifice, and camaraderie. Soldiers from different backgrounds and ranks find themselves caught in the fray, displaying acts of heroism and facing the harsh realities of war. German forces, anticipating an invasion but unclear on its exact location, scramble to mount a defense, adding to the unfolding tension. The interconnected stories build up towards the climactic confrontations central to the operation's success, presenting a multifaceted view of one of the most significant days of World War II.