The Wall isn't a movie so much as an amuse-bouche, and one that's none too amusant. I rescind none of my faith in director Doug Liman, who has made a few good films, a couple of great ones, and only one that's actually bad, 2008's Jumper, but this first of his two 2017 releases (the second being American Made) is at best a tossed-off lark that taxes its creator not at all, and at worst feels like some exercise that everybody involve decided to joylessly grind through for reasons which I'm sure made sense at the time, but don't come through in the finish project.

It's yet another in that inexhaustible list of stunningly unexceptional movies whose script showed up on one edition or another of the Black List, which purports to showcase the best unproduced screenplays in Hollywood, but seems to have birthed a disproportionate share of slack mediocrities. I don't think I blame writer Dwain Worrell for that, in this case; The Wall has a terrific hook and an airtight thriller structure. That hook being, we're in Iraq, sometime in 2007, shortly after one of the many times that the United States was, no for serious this time, definitely about to start figuring out a strategy to begin withdrawing troops. Two of these troops have been sent into the desert to check out an oil pipeline under construction: Staff Sergeant Shane Matthews (John Cena), a sniper, and Sergeant Allen Isaac (Aaron Taylor-Johnson), his spotter. All is going fine, till quite out of nowhere, Matthews is mortally shot by a never-seen Iraqi sniper, and in his attempts to save Matthews, Isaac is shot in the leg. Matthews is left to bleed out in the desert sun, while Isaac is able to find shelter behind a crumbling wall, with nothing but a busted radio, which he uses to attempt to call in backup; he's able to find just one voice (Laith Nakli), and gives away a rather indiscreet amount of information before figuring out that this is the voice of the very same sniper keeping him and Matthews pinned down.

The single location survival thriller genre has a spotty track record, to be sure, but The Wall is at the very least smarter and more nimbly-plotted than, say, Frozen, or fellow 2017 release 47 Meters Down. Which isn't saying much (47 Meters Down is about as nimble as an elephant on an escalator), but it still feels like the film ought to be more than the yawning splat of nothing much in particular that it turns out to be. It's too easy to put most of the blame on Taylor-Johnson, but I can't say that I'm particularly bothered by that. So yes, let's put lots of blame on him, even if it's only for the inadvertent crime of not being John Cena, a WWE wrestler who managed to follow the Dwayne "The Rock" Johnson arc from "why are they putting this man-shaped meat pile into films?" to "he is a comic genius and I will follow him anywhere he wishes to go" in the span of, like, five months. And is Cena giving a performance for the ages here? No, but he's got just oodles of charisma and screen authority as a confident military man, quite eradicating any lingering 11-year-old memories of his starring turn in The Marine. Just kidding, nobody has lingering memories of The Marine, most likely including John Cena.

At any rate, the trade-down from Cena to Taylor-Johnson has a deflating effect not seen since the 2014 Godzilla, when the same actor stole the leading role right out from under Bryan Cranston. He's just not much of a screen presence, Taylor-Johnson; and he's a little too stuck in his own head, letting us see him think, to sufficiently sell the increasingly frazzled, sun-baked terror that creeps in (or ought to, anyway), as Isaac grows increasingly desperate at the taunts of his unseen interlocutor. But honestly, The Wall's problems go deeper than just one thoroughly miscast leading man. It's only exciting in fits and starts, typically when we learn some new fact about the mysterious sniper, who either is or isn't the famous sniper Juba (who may or may not have existed). Liman and his collaborators - cinematographer Roman Vasyanov, editor Julia Bloch - openly treat this material as little more than an exercise in staging a full feature in a tightly-constrained circle around Isaac and his decaying wall, and not even an exercise they seem terribly interested in executing. The film relies on a damn lot of samey close-ups, with the dialogue between Isaac and his tormentor providing virtually all of the momentum. And that's just not even close to enough. Take out Nakli's insinuating melodramatic vocal performance, and you've quite removed 90% of what makes The Wall an effective thriller; though his performance counts for a lot, and the remaining 10% includes some good moments of tense stillness, the awful feeling of confused waiting for something, which will probably be bad, though of a badness that cannot be predicted.

The only other thing to mention is the film's profoundly confused stance on U.S. meddling in Iraq. That Liman, director of the very earnest and somewhat watchable 2010 message thriller Fair Game would take on another film criticising the war makes sense; and as far as I can tell, The Wall does indeed think of itself as a highly critical anti-war parable. But it's a damned erratic one. The sniper is a singularly under-developed figure, whose narrative function is little more than Jason Voorhees: the unstoppable menace with an unnerving ability to strike out just exactly when you thought it was safe. And to that end, he's typically written as a malevolent entity, cackling with glee at his wicked craftiness. Yet just often enough that you can't stop noticing it, he'll shift gears to attack the actions of the Americans - the titular wall, we learn about midway through, was part of a school that was bombed into oblivion by the American military - and the film shifts gears right along with him, treating this as tragic cruelty, the sign of swaggering imperialists who've done a great evil in the world.

This fucks the film up twice over: politically, it's incoherent, trying to depict the Iraqi sniper as both a movie monster and the voice of moral reason, and in so doing mangling whatever message it thought it had. Narratively, it makes it impossible to root against him, and so the whole thing just turns into a slightly sour-tasting waiting game, as we see whether the one person we don't like is able to survive the onslaught of the other person we don't like. The film isn't without its tense charms, and the opening 20 minutes or so are an awfully strong military procedural, but the whole experience just feels like a big sack full of nothing at all, constantly interrupting itself all the way down.