As The Wall opens, Sgt. Isaac (Aaron Taylor-Johnson) and Sgt. Matthews (John Cena), two soldiers serving during what’s supposed to be the final days of the Iraq War in 2007, are bored. Camouflaged and perched high above the scene of a skirmish that’s left eight contractors working on a pipeline dead in the middle of the desert, they try to determine just what took them down while concluding they’re both sure — or sure enough — that who ever killed them is gone. Barring some kind of “super sniper,” it’s obviously the work of some long-departed enemy fighters. After a long stretch spent observing the scene and teasing each other, they’re ready to complete the mission, confirm their theory, and head out. So, after trading some nervous jokes, Matthews decides to investigate. Then he sees that body after body has been taken out by a headshot. Then the bullets start to fly from some unseen location and he’s hit, immobilized, and possibly killed, leaving only Issac to figure out what the hell is going on.

It’s a tense opening for a film that has a hard time keeping out the same level of intensity, though one that deserve a lot of credit for depicting the war from such a limited perspective that it forces viewers to consider what it’s like to be in Isaac’s boots. Rather than attempt a sweeping depiction of the war experience, it zeroes in on a few awful hours in the lives of a pair of soldiers already rattled by the dangers they’ve run into before — situations that pale next to the one they find themselves in now. Then, to make matters worse, Isaac finds himself wounded, pinned in behind a Wall, and in a radio conversation with the unseen sniper, a famed insurgent known only as Juba (Laith Nakli).

Written by first-timer Dwain Worrell, The Wall plays at times like it could work just as well, if not better, as a play. Director Doug Liman (Edge of Tomorrow, The Bourne Identity) brings, as always, stylistic flair to the movie. But apart from the earliest scenes, the tension mostly comes from Isaac’s conversations with the sniper, who taunts him as he tries to draw out details of his life (shades of Phone Booth).

The problem: It’s never quite enough tension. Johnson, who’s been the dull center of a lot films, gives an intense performance as Isaac. He makes his wounded, parched character seem desperate enough to try almost anything to get out the fix he’s in. But as the film progresses his conversations with the sniper start to feel more scripted than felt, particularly when Juba draws out a pained back story that could have come from virtually any war movie since John Wayne stormed Iwo Jima.

That said, The Wall isn’t, in most ways, a typical war movie, and at its best it suggests the terror and helplessness that comes from being on the battlefield by staying so close to Isaac and not letting us move away from his mounting sense of doom. And it gets bonus points for a finale that’s unsatisfying while also feeling like the truest possible conclusion it could have. Whatever its shortcomings as a movie — and it gets long and dry and dull for a good long stretch — The Wall stays true to its own narrow, hellish vision of war.