Ben Wheatley is happy that these are small-budget movies made on his own terms. After finishing High-Rise with Tom Hiddleston and Luke Evans, he turned to Free Fire. The idea came from reading transcripts of real police shootouts that are far messier than the movies ever portray them. "That was the beginning point for me," Wheatley says. "I thought maybe there's something in this, a procedural thing about people in a gun battle in real time. I'm not saying that Free Fire is a documentary or massively realistic, but it relies on some of that realism."

Ben Wheatley at the 2017 Empire AwardsBen Wheatley at the 2017 Empire Awards

Set in 1970s Boston, the film was shot in a warehouse in Brighton, England, over six weeks with an eclectic ensemble of actors led by Brie Larson, who arrived straight from filming her wrenching Oscar-winning role in Room.

"I think that's the process with me," she says. "You shake it off by jumping into something else that uses a completely different muscle. With something like Room, I was like, 'Next year or two of jobs, I can't cry. I can't cry anymore!' I'm looking for something to laugh over. After long enough, your body just needs to keep the hydration. You can't keep crying it out."

For Armie Hammer, what drew him to the project was the creative team. "It was the opportunity to work with Ben, and it was the chance to make a movie in Brighton in the summer," he laughs. "It was a movie that you read the script and you go, 'I don't think there's been a movie like this in a long time.' It was really refreshing."

More: Read the review for Free Fire

And of the experience, Sharlto Copley says it was easily one of his career highlights. "The process of making the film was just so, so actor-friendly," he says. "I'd heard this from my agent about Ben being somebody actors just truly rave about. You couldn't ask for a better situation: everyone's in one place and you're kind of doing it as a play. Ben shoots very fast, it's shot in order, everything's real, practical."

Wheatley says that shooting in order was important to "keep the continuity of the clothing and the wounds" during the epic shootout.

His next project is Freakshift with Alicia Vikander. "I just want to do different stuff all the time," he says. "So I think there's still a cowboy film in me and maybe a rom-com, but not a musical. I f**king hate them."

Watch the trailer for Free Fire: