Jack O'Connell in "Starred Up"

More than a few times since David Mackenzie’s ferocious “Starred Up” stormed through the festival circuit at the end of last year, it’s been commented upon that the prison-set drama marks a departure for the director.‎ However, since breaking through on the international scene with “Young Adam” just over a decade ago, Mackenzie’s signature has been not to have one‎, except for the immense passion he’s channeled through each of his projects, so naturally when the script from a former prison counselor named Jonathan Asser – about an ‎irrepressible young man doomed to repeat the same mistakes as his father, with whom he now shares a prison block, unless he changes his ways – crossed the desk of the director’s production company, the chance to do something different was too much to pass up.

“It was a hard and straight film on the surface, but underneath it there was a human heart and there was an opportunity to touch on a little bit of humanity,” says Mackenzie. “I was waiting for that type of film to turn up on my doorstep and it did.”

Yet it’s one thing to have the right script fall into place, but quite another for the filmmaker to be ready for it and part of the pleasure of “Starred Up” is seeing Mackenzie finally put it all together for his finest film to date. After challenging himself with each successive film – his last two may have been simple romances on the surface, but set against the T in the Park Music Festival in Scotland (“You Instead”) or, only slightly less chaotically, the apocalypse (“Perfect Sense”), they emerged as something entirely different – Mackenzie is clearly as invigorated by the experience of his latest film as his cast onscreen, which features an wildly unencumbered, starmaking turn from Jack O’Connell as the 19-year-old Eric and a beautifully barbed performance by “Animal Kingdom” star Ben Mendelsohn as his circumspect yet still dangerous dad.

Like Mackenzie’s other films, a description of “Starred Up”‘s premise, built around Eric’s gradual unmooring of his anger through a series of group therapy sessions led by a sympathetic counselor (Rupert Friend), doesn’t quite do it justice, but it shares the swagger of Eric from when we first meet him, the camera free to swing around to capture all the action within the real-life prison filming took place in with a kinetic energy that likely emerged from Mackenzie’s decision to employ two editors on set to work on scenes as soon as they were shot. The film is at times brutal, tender, and above all else, arresting, and shortly before its American release, Mackenzie stopped for a second in the midst of a whirlwind press tour to talk about how his experience on “Starred Up” changed how he views directing, getting past the inarticulate nature of male expression and being as honest with the film as he could be.

Jack O'Connell in "Starred Up"In recent years, I’ve felt you’ve been attracted to stories that are as much about the worlds with a specific set of rules as much as the characters who live inside them. Do you think there’s any truth to that?

I’m not sure whether I agree. I find myself relating to stories that feel like they’re about characters who are struggling to deal with themselves in some way or another, more than I am about necessarily the worlds. In order for a story to kind of hit me, it’s much more about the people than it is of necessarily about the world.

You’ve said that you could identify with both the father and the son in this film. Age-wise, you fall in between those two ranges, so in terms of perspective, did it feel like the right time to make this film?

In other film assignments, I’ve had a little bit of mother-son stuff but they’ve been side characters, and I’ve never attempted to do anything dealing with direct father-son stuff. I’m sure it’s related to the fact that I find myself as a father too, although my kids are a lot younger. The idea of the male — inarticulate, who emotionally locks down and is a bit uncomfortable with themselves, but also able to put on a good front kind of characters having to kind of find their way into expression and having to reach out to each other — feels strong to me. Male expression is also interesting to me because it’s often not very good. It’s often a real struggle for fathers and sons.

Rupert Friend and Jack O'Connell in "Starred Up"One of the most interesting things about this film in terms of your career is that there’s always been a strong female counterpoint for the men in the film. Was it interesting to do something set entirely in a world of men?

What’s really interesting is that the presence of women is everywhere in the film to some extent. The only proper female character is the boss, but the theme of the mother is very strong in the minds of all of the prisoners and it was very interesting to do a film that’s set in a very much an all-male world where the absence of women also becomes a weird presence.

How did the shooting style for this film come about? It’s set in a prison and yet it feels so untethered.

It’s a good question because in all the confines of the prison both architecturally and narratively, I felt more in control of this movie in a way than I felt of any other movies I’ve done. As a result of having the confines of the jail at the core of the creative hub, there’s quite a lot of freedom. Improvisation was encouraged and because we shot sequentially, we were able to explore the material.

I talked with Michael McDonaugh, the director of photography, about a shooting style that was very much about letting the action dictate the frame rather than the frame dictate the action. Although Michael and I both have strong aesthetic senses and that’s there in the film, we could discipline ourselves not to let that get the better of us and to let the action define itself. Obviously, the jail offers a lot of cinematic opportunities. The multilayers of the floors, the frames within frames, the corridors, and just the textures of it are actually quite inherently cinematic, but we were never kind of gloating on those opportunities. We were always trying to let the reality of the situation do the work for us. As a byproduct, we were usually able to get more interesting looking shots along the way.

Do you view directing as something different than when you first started?

I’m constantly trying to evolve the process. The process itself becomes or can become oppressive — it becomes predetermined. I’m always trying to do things a bit differently in order to keep it alive, just like I’m always trying to choose film subjects a little bit differently from the last one just so that I don’t feel like I’m treading the same ground.

When I first started directing, I thought of it as being a completely visual medium that was about predetermining frames and movements and being very specific and organized. As I’ve become more mature as a director, I’ve learned to be much more fluid, much more intuitive, much less interested in the predetermined shots, much more about the moments and making things feel alive, extracting the energy from the scene. I’ll look at scenes as being a set of ingredients that you work with and directing as a way of embracing the narrative and the ideas but also allowing all the people within the team to shine by being allowed to explore the material in their intuitive way. It’s about creating a protected environment to allow the great things to happen — I used to think it was all about pushing things whereas now it feels more like allowing things. I’m much more happy with the idea of it but it’s harder to define. Certainly for this film it was a very positive example of that.

Ben Mendelsohn and Jack O'Connell in "Starred Up"This seems to be one of your most well-traveled films. Has it been nice to see the reaction?

It’s a weird one for me because the subject matter is so intense. You wouldn’t think so, but all the way through the process, it’s been a positive experience. From when I first met Jonathan [Asser, the screenwriter], who’s a very forthright person, prepared to put his vulnerability and honesty right on his sleeve, I took that honesty and made the film with as honest and open-eyed approach as I possibly could. We finished it quickly. We made it with integrity and it went out into the world in those terms. Traveling with it has been a pleasure.

“Starred Up” is open in New York at the IFC Center and the Elinor Bunin Monroe Film Center and will open on September 5th in Los Angeles at the Sundance Sunset, Chicago at the Facets Cinematheque, Philadelphia at the Roxy Theatre, and Seattle at the SIFF Cinema. A full list of theaters and dates is here. The film is also available on VOD, Amazon, Vudu and Google Play.