Nick Gillespie has worked as a camera operator for Ben Wheatley since 2011’s Kill List. Now for Gillespie’s directorial debut, Wheatley put his weight behind the film, Tank 432 (formerly known as Belly of the Bulldog), as a producer. Like Wheatley’s films, Tank 432 (which had its world premiere at the Fantasia International Film Festival) is a cerebral story – one that offers plenty of questions and just enough answers to surely frustrate many. This bad boy is all mood and atmosphere – at times feeling like an exercise in tension and dread more than a narrative. For most of its brief 80 minute running time, the characters of Tank 432 are just as confused as the audience.

Gillespie isn’t interested in holding our hands through his fever dream either. We’re dropped in media res as soldier Reeves (Rupert Evans) is being chased through the woods by an unseen assailant. Whatever it is nipping at his heels – human or supernatural – Reeves is scared shitless of it. He meets back up with his unit, led by no-nonsense Smith (Gordon Kennedy). Everything is in shambles. Capper (played by the always phenomenal Michael Smiley) has an excruciating leg injury. Another guy is losing his mind with remorse – as if whatever the hell just happened is entirely his fault. The medic Karlsson (Deidre Mullins) is doing her best to squash every bit of tension (mainly through sedatives). As they desperately search for some sanctuary, Smith drags two hooded captives behind him.

In their frantic retreat, the unit comes across decapitated corpses and a survivor trapped inside a shipping container. Whatever caused all this carnage, the survivor is left mentally broken by it. After making some tough decisions, the unit finds their salvation inside a broken down tank. They lock themselves inside – captives and survivor included – and are given a brief respite knowing their mysterious enemy cannot huff and puff and blow down this house of iron.

The already claustrophobic situation quickly devolves into paranoia, suspicion, and a litany of others way to say “not good.” Small clues are given – like Smith’s notebook and a cache of files found inside the tank, but just as Gillespie offers up some hints, more questions are presented. A major layer of the mystery is peeled back when one of the captives questions Reeves on what it is they’re running from. If the captive doesn’t know, and Reeves’ unit doesn’t know, then who the hell knows what’s outside the tank? Anybody? Smith? The survivor?

During their second night in the tank, Reeves gets some spooky visions. We’re shown flashes of horrible monsters with black muzzles, hellfire, and other gruesome sights. It’s all part of the nightmare Gillespie is creating. We don’t know if these visions are prophetic or things that already happened to Reeves and the unit in the past. Or are they just a drug-induced vision? What is in those injections the medic keeps giving everyone, anyway? Believe me though, they’re not just superfluous images, these visions. There are payoffs for them.

Like Wheatley’s films, particularly Kill List and A Field in England (also worked on by Gillespie), Tank 432 is more about the atmosphere and world being created, not the story particulars themselves. Gillespie manages this tone remarkably well – from the first disorientating shot to the gloomy, revelatory closer. Along the way the audience is a participant. In my head I started accusing Smith. Near the end, when Michael Smiley is gleefully throwing an unidentified red powder around (what was up with that powder?!), I was pretty sure I had it all figured out. Well, maybe not it all. And yeah, my conclusions were tossed out the window by the end.

The unit exists in a firm command and obey dynamic. Smith commands and Reeves and others obey. Even when everyone mistrusts Smith’s intentions, he refuses to relinquish command. Cramped down in the belly of the bulldog, Smith’s power is his only form of survival. The tension within the tank becomes like this kinetic ball feeding off of everyone’s fear and paranoia. Outside the tank, there’s a great expanse of land, which, considering the unknown entities lurking there, at times is even more terrifying than the powder keg inside the tank.

There is an emotional coldness to the film that makes the revelations rolling over Reeves in the end feel a little hollow. As engaging as the story is, there was still this coldness to the whole thing that kept me at arms’ length. I think a little more characterization could’ve gone a long way in making Tank 432 more absorbing.

Still, its vagueness is its strength at times and Gillespie proves himself a skilled writer/director in his own right with his ambitious debut. If you’re frustrated by ambiguity, you’ll want to avoid this one. But if you can get your rocks off on atmosphere and tension alone, do not miss it.

The film screened at the ongoing Fantasia Film Festival in Montreal.