Framed as a World War II epic and a thriller, Christopher Nolan’s Dunkirk is that at first glance. But beyond the derring-do of Royal Navy men, fighter pilots, and civilian sailors as 400,000 men await rescue on a beach after a disastrous battle, is a more intimate drama of courage and cowardice and emotions in between. That is the most intriguing aspect of Nolan’s ambitious film, and the one where it falls down, betrayed by a dearth of real flesh-and-blood characters.

The outcome of the 1940 battle around the northern French village leaves the defeated Allied soldiers stranded a scant 26 miles away from the English coast, or as one officer observes, “You can almost see home.” But with few ships available in the area that, at any rate, can’t land on the beach and with precious little air support to provide cover, the British hit on an outside-the-box solution to the problem. The Navy drafts fishing boats and pleasure craft and their crews, a civilian armada that can go where destroyers can’t.

Nolan fashions a sometimes-discombobulating story that zigzags back and forth between three separate strands. There are the men on the beach. Among them are a group of young infantrymen that include newcomer Fionn Whitehead and One Direction singer Harry Styles (in his acting debut), who are loathe to wait for rescue. They want to go home. Now. In contrast are the officers, including Colonel Winnant (James D’Arcy) and Commander Bolton (Kenneth Branagh), who embody courage in the worst-case scenario as they discuss the long odds facing them.

In the air, a small contingent of Spitfires, including pilots played by Tom Hardy and Jack Lowden, engage in dogfights with German Messerschmitts, a desperate skirmish to keep themselves airborne while protecting the ships at sea. On the water, Mr. Dawson (Mark Rylance), the skipper of a yacht heading toward Dunkirk with his 19-year-old son Peter (Tom Glynn-Carney) and 17-year-old family friend George (Barry Keoghan), is the representative of the civilian volunteers.

Clocking in at under two hours, Dunkirk, nevertheless, occupies a large canvas. The cinematography, production values, and special effects are breathtaking. The air skirmishes are thrilling, the drama’s overall vibe is tense. The disaster looming at sea, from a small, leaky boat threatening to capsize to destroyers mortally struck by bombs, bucking and listing as they sink into the water, is palpable. Dunkirk may not reinvent the war movie, but it is effective.

What the film lacks is the human element. There are no fully formed characters in the movie. Everyone is a type. Some actors are able to transcend the script’s limitations. Whitehead is especially effective in conveying sheer terror and his character’s commitment to survival. Cillian Murphy is also very good as a shell-shocked soldier reduced to a ball of quivering panic. But most of the cast, including actors of the caliber of Branagh and Rylance are stuck with cliched dialogue to go with their hoary stiff upper lips.

That lack of humanity is costly. For all its thrilling spectacle, Dunkirk has none of the power of an All Quiet on the Western Front, Gallipoli, or Saving Private Ryan. The stakes in Dunkirk are every bit as high as they are in those and countless other war movies. But it is hard to care when there is no beating heart in the movie. That is a flaw that prevents Dunkirk from achieving the greatness to which Christopher Nolan so clearly aspires. –Pam Grady