The most brazenly crowd pleasing effort yet in the career of British filmmaker Ben Wheatley, Free Fire makes the most of a simple, but exciting premise – once again written by frequent collaborator, co-editor, and partner Amy Jump – that offers up not only considerable thrills and twists, but also a huge amount of belly laughs and chortles. It’s not a particularly deep film, and not even half as cerebral as Wheatley’s other cinematic offerings, but as an excuse to stage what amounts to 10 minutes of set-up and 80 minutes of people shooting at each other, it’s as great as one would hope and expect.

At an abandoned waterfront warehouse in Boston in the late 1970s, a group of representatives and goons-for-hire working on behalf of the IRA (Cillian Murphy, Brie Larson, Michael Smiley, and Sam Riley) are attempting to purchase a stockpile of illegal weapons from another batch of criminals (Sharlto Copley, Armie Hammer, Babou Ceesay, and Jack Reyor). Things go awry when a previously unknown dispute between two members on opposite sides turns violent, leading to a massive shootout and fight for survival. Misunderstandings and double crosses abound, and a pair of snipers hidden in the rafters trying to sabotage the job on behalf of an inside man don’t help matters. There are only two goals (outside of not getting killed): get to a phone to call for back-up in the firefight and leave with the briefcase full of cash if escaping with the guns isn’t an option.

While some might accuse Wheatley (Kill List, High-Rise) of backpedalling or regressing following his headier recent efforts, it’s undeniably a great bit of fun. He makes the most of his story and setting, with the chaotic action seeming more sprawling and grand than it probably would be in such a location. Through clever use of sound design and careful editing, Wheatley and Jump make sure that even if the audience isn’t paying attention to every character at the same time (and honestly who could given all the chaos), they will know exactly where they are situated in the warehouse. On screen, two people can be having one conversation, while off screen the audience can hear a second dialogue moving along at the same time. It’s a delicate trick that ensures every member of the cast always has something to do, and although the film is a fairly straightforward, comedic shoot-‘em-up and survival thriller, Free Fire can’t be accused of not delivering the goods in the best, most thoughtful package possible.

While the fireworks are a huge attraction, the performances carry the day here. Every member of the cast knows how to make Wheatley and Jump’s witticisms sing to almost operatic degrees. Copley’s preening “child genius” arms dealer might be the actor’s greatest performance to date; one that knows how to use the performer’s sometimes purposefully annoying charms to great effect. The always underrated Reynor’s hotheaded, bespectacled tough guy, and Riley’s unhinged Southie crackhead are constantly going toe-to-toe and serve as the driving force behind the shootout in the first place, and they make the most of their interactions. Murphy, Larson and Smiley all deliver highly memorable performances with just enough gravitas and sarcasm to hold the lunacy together, but it’s Hammer’s droll, unflappable, hirsute, pothead mastermind who steals every scene and walks off with an already strong film. Whenever Hammer appears on screen the audience is in for all of the film’s most memorable bits. The cast also exhibits great physical acting chops since just after the halfway point, everyone is wounded and hobbling around. That can’t be easy to keep up.

In some ways, Free Fire isn’t only the best vehicle for the talents of Copley and Hammer, but also for Wheatley, who proves that he can deliver an unpretentious potboiler if he ever feels so inclined (although this will shock no one familiar with his short film and television work). At one point in Free Fire, a character makes a crack about “the magic 90 minutes,” or the amount of time before someone with a relatively minor bullet wound bleeds out and dies. Such a self-referential line is no coincidence, and Wheatley knows exactly how long he can get away with such a fun, extended parlour trick. He could have a great career making just these kinds of films, but here’s hoping that he’s able to still stay a bit weird if he makes the leap to bigger, more mainstream fare.