For writer/director Steve McQueen, “Blitz” is not just another war story.

The film is set during the Blitz in the 1940s, when the city of London was under the constant barrage of bombs from the German army. McQueen decided, though, to depict the horror of war through the eyes of a child named George, played by Elliot Heffernan, who was sent to the countryside for safety, by his mother, Rita, played by Saoirse Ronan.

“What was so important to me was to give a platform to things that were unseen that needed to be seen, that were true and needed to be told,” he says.

McQueen was inspired by a photo he came across while doing research for his anthology series “Small Axe,” of a small Black boy holding a suitcase. “It was just this sweet, beautiful, cute boy, and I though, Ok, I need to know your story,...