World War II is almost certainly the big screen’s most immortalized conflict, and for good reason. It broke just as cinema was beginning to mature as a form of entertainment, and footage from the front narrated by peppy tales of victory was part of many people’s moviegoing experience. What’s more, though, the outlines of World War II could be boiled down to clean tales of good versus evil, bravery versus cruelty — the sort of stories that make good two-hour feature films.

As historian Elizabeth Samet argues in her excellent 2021 book “Looking for the Good War,” the heroism performed in Hollywood’s World War II movies soon became the filter through which all American involvement in foreign wars was seen and encouraged. In the aftermath of war, she writes, “causes are retrofitted,” and “participants fondly recall heroic gestures.” The tendency extends far beyond America, because the tale of valor richly rewarded and goodness winning the day is the kind of World War II movie we want to see — and the kind we mostly have.

Yet most stories during the war didn’t end in glory and goodness. They ended in death and dismemberment, heartache and trauma, lives destroyed, families ripped apart. Yes, the good guys won. But winning a war still means losing.

The British film industry is hardly immune to the triumphalist tales, and watching “Blitz,” I began to have a strong suspicion that those are precisely the movie’s target. Filmmaker Steve McQueen, whose film “12 Years a Slave” won the Oscar for best picture in 2014, works with the eye of a protesting artist, as aware of form as he is of content.If you look directly at “Blitz,” the story is fairly straightforward. It is 1940, a year into the war. Rita (Saoirse Ronan), a single mother working in munitions, lives in a shabby London neighborhood with her 9-year-old son, George (astounding newcomer Elliott Heffernan), whose father was a Grenadian immigrant, and her father, Gerald (played by musician Paul Weller). Like hundreds of thousands of other children, George is about to board a train for the British countryside to be protected from bombs. It’s the Blitz, and London is under siege.

But things go awry almost from the start. George is livid to be separated from Rita, who is gutted to be sending him away. He tells her he hates her at the station, a bit of childish petulance that nonetheless wounds them both. Then, a bit outside of London, he decides he’s had enough of this, and he jumps off the train.The movie bears comparisons to Dickens, both for George’s plight and for the depiction of class divides across a war-torn London.

But there is something else going on narratively here. For one, McQueen makes a point of integrating into the film what is rarely seen in movies of this sort: a sharp depiction of racism among Londoners, the enraging sort that has so calcified it still surfaces when people are just trying to survive. George is the target of relentless insults from other children, shopkeepers and random people on the street. Ife is as well, despite his uniform. That the ugliness of prejudice and xenophobia appears even among those who proudly consider themselves opponents of Hitler’s murderous policies flags a deep contradiction and capacity for self-deception in the human heart.

But the episodic nature of “Blitz” has another meaning. Opening text of the film somberly explains that during the bombings, 1.25 million people left London, and more than half of them were children. Thus primed to assume this is a story about evacuating, we’re a bit surprised when George jumps from the train and heads back to London.

In fact, this pattern repeats throughout the film: George seems to be beginning a story — the boy and the orphan brothers; the boy and the kind mentor; the boy and the thieves; the boy hiding from the police in the ruins — but it’s always finished almost before it begins. Each story is aborted before it gets going.

And it’s not just George’s stories, either. In one remarkable sequence, a group of revelers is in an underground jazz club where an all-Black band performs for a mostly white crowd. They’re laughing and dancing and drinking, but then the planes are heard overhead, and their story abruptly ends.

This sort of start-and-stop can feel a little frustrating, like listening to a DJ who keeps skipping to the next track just as the beat really drops. But it’s clearly purposeful — as is the fact that the pivotal act of heroism in the film is maddeningly, brilliantly kept out of frame entirely. Often the camera (Yorick Le Saux is the cinematographer) pulls back to overhead shots of London, gradually turning to rubble night after night. This is, it suggests, the real story.

Taken all together, the idea emerges. We tell ourselves stories of wartime heroism, of resilient unity in the face of destruction, of the power of the human spirit for a clear reason: We want to raise our spirits and inspire ourselves to great things.

But the truth about history is always more complicated. People are prejudiced and cruel, even people who believe they’re on the side of the good. Stories do not always fit the narrative arcs we want for them. And even heroes — especially heroes — find themselves, sometimes, just weeping in the ruins.