“Blitz,” set in London during World War II, might technically be Steve McQueen’s first war movie. But struggle and survival has long marked the filmmaker’s tough and tortured work.

In last year’s “Occupied City,” McQueen juxtaposed past and present, death and life, and some of the same collisions are found in the 1940-set “Blitz.” It’s told largely from the perspective of a 9-year-old boy, George (Elliott Heffernan), whose single mother, Rita (a steely Saoirse Ronan ), has made the anguished decision to send him to the countryside with thousands of other schoolchildren fleeing the Blitz.

“Blitz” properly gets underway once Rita leaves George at the train station. The parting is bitter (“I hate you,” George says on the platform) only because their bond is so evidently strong. It’s not long once aboard the train that George sees a chance to flee and hops off. “Blitz” proceeds as George’s odyssey in trying to get home.

It’s an awkwardly condensed tale — the film takes place over one day but feels like a lifetime — that clunkily cuts between George and Rita. “Blitz” feels stuck between a conventional war drama and something more adventurous and probing. It doesn’t coalesce the way McQueen’s best work does, but the frictions that drive “Blitz” make it a singular and sporadically moving experience.

A representative sequence happens early in the film. George, who’s Black and surely feels some growing anxiety leaving London, climbs into a passing train only to find three young brothers are also stowaways there. After a tense moment, they find camaraderie together. Riding atop the train, they seem almost carefree. But moments later, when they’re fleeing authorities at the trainyard, one of the boys is killed in an instant by a moving train.

The film stays close to George as he makes his way closer to home in Stepney Green in the East End. “Blitz” is far less concerned with the aerial bombardment above than the festering prejudices and injustices on the ground.

There are moments of uplift, or at least temporary relief. One comes when Rita, who works in a munitions factory with a Rosie the Riveter headscarf, sings for a BBC radio program from the factory floor. Once Rita learns that George is lost, there’s an ill-fitting side plot of her feuding with an unsympathetic boss, arguing with those in charge of the evacuation and her attempting to find George with the help of a police officer.

Again and again we see, though, that going against a tide of indifference takes the conviction and courage of individuals. That includes the activist Mikey Davies (Leigh Gill), who makes a stirring speech in a shelter. And, most of all, it includes a Nigerian ARP warden Ife (Benjamin Clémentine), who George meets outside a store advertising coffee and sugar from Africa with caricatures of Black faces. Clémentine, the talented singer-songwriter, has a radiant presence that warms a fiercely unsentimental film. Ife imbues George with a pride and confidence with himself as a young Black man. For his part, the young Heffernan shows no strain in carrying the movie, his first.

Ultimately, that there is a war on in “Blitz” may not be its defining feature. The London under siege in McQueen’s film is as much at risk from injustice as it is German planes. For George, Rita and the others pushing back, resistance isn’t just wartime survival. It’s a way of life.

MPA rating: PG-13 (for thematic elements including some racism, violence, some strong language, brief sexuality and smoking)

Running time: 2:00

How to watch: In theaters, streaming Nov. 22 on Apple TV+