Christopher Nolan is the master of subtly creating unease -- and also the master of putting Tom Hardy in a face-covering mask.

Nolan showed a 5-minute clip Wednesday of Dunkirk, his World War II drama epic due in theaters July 21, and if you thought the teaser they released last August was intense, just wait until you see this thing.

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The new footage was revealed at Cinemacon, the annual gathering of movie-theater owners and Hollywood studios, and it could very well be our first extended look at one of the year's biggest Oscar contenders -- and biggest heart-stoppers.

"I believe Dunkirk to be one of the greatest stories in human history ... it's one of the stories that British people grow up with. It's in our DNA," Nolan said of the Dunkirk evacuation, in which nearly a half-million Allied soldiers were trapped at the beach in 1940, cut off by the German army and on the verge of slaughter -- were it not for a major impromptu civilian effort that came to be known as the Miracle of Dunkirk.

What we already know from previous Dunkirkteasers: Tom Hardy plays a Spitfire fighter pilot who's patrolling the skies over the beach. What we didn't know: He's about to be in seriousperil.

Here's what we saw in Wednesday's footage reveal (sorry, One Direction fans -- we didn't get a glimpse of Harry Styles this time).

Two British soldiers are carrying another on a stretcher (Styles? Could be!) across the beach, toward one of the precious few military evacuation boats.

"That's two minutes -- you've missed it," they're told, and it seems they are out of options.

Meanwhile, on another shore, Mark Rylance (playing a civilian boat owner, who's lending his craft to the effort) is gearing up to go help out. "Some men across the channel at Dunkirk need taking off," he tells a boy, who sees the dozens of life jackets being loaded on.

"Somemen?" the boy replies.

In the skies overhead, Hardy is leading a three-plane sortie of Spitfires. With a Bane-like flight mask covering his face, he sounds supremely calm as they get into a dogfight with approaching German aircraft.

(A steady drumbeat over the images is picking up speed, like a too-fast heartbeat that's getting faster.)

"He's on me!" one of Hardy's mates cries, but Hardy has settled his Spitfire in behind the pursuing Luftwaffe: "I'mon him," he says.

Back on the ground, the two soldiers carrying a stretcher have encountered a major hole in the wooden bridge, which is spanned by a single plank. They'll have to run their patient across -- and do. The other soldiers cheer.

Hardy opens fire on the German plane and bullets light up the enemy's fuselage. "He's down for the count," Hardy says coldly, as he and the sortie fly over a giant frigate filled with men.

Then Hardy's plane runs out of fuel.

As the drumbeat hits an unbearable pace, he's dead-sticking his plane over Dunkirk.

The rest ... will probably have to wait 'til summer.