Dunkirk is a story about war. The World War 2, when the Britishers were made to retreat by the Germans, the German Empire was strongly built with enough Mastermind plans and their execution was in the best way possible.
So it were the Soldiers of British, who could not return back to their respective places, they were all stuck at Dunkirk, the french coast. So it was Germans, who had control over the place. So it was pretty dangerous for the Britain Air forces and the other Naval forces to penetrate into Dunkirk dock, and save their men. And keeping in mind, the dangers involved in going to that area. The rescuers enter the endangered region.
This gives a feeling of real war ongoing, there were many personal issues also displayed, which were regarding emotional and sympathy based issues, but adding up the whole. The remainder gives up a positive response of the movie. The characters have done their role in a much better manner.
This is a must watch movie for the viewers who like thrilling movies.