Dunkirk is based on a true World War II story. From May 26 to June 04, 1940, Allied soldiers from Belgium, the British Empire, and France were completely cut off and surrounded by German forces at the beaches and harbor of Dunkirk, France.
In three separate storylines—land, sea, and air—and without a clear-cut lead character, Dunkirk tells of the efforts to rescue the Allied troops. Fionn Whitehead is a British soldier stranded on the beach in the land segments, Mark Rylance is a civilian crossing the English Channel in his small yacht to aid in the rescue in the sea portions of the film, and Tom Hardy is in the air as an RAF Spitfire pilot attempting to shoot down German bombers.
All three stories are intercut with one another, but they have different time frames. Often, the intercutting maximizes suspense, but occasionally it is a little confusing.
Dunkirk is directed by Christopher Nolan (The Dark Knight Trilogy, Inception, Interstellar) who is known for visually stunning epics, and this is no exception. The opening scenes on the beach during an attack from the air are haunting. Nolan really puts you in the middle of the action, thanks to his camera placement and the excellent sound effects. When you are in the cockpit with those pilots you can hear it shuddering. You feel like you are there.
Dunkirk is quite a cinematic experience, and is one movie you should see in IMAX.