When Clio Barnard went out to cast her latest film “Dark River,” she made no secret of the hard work it would entail, requiring an actor and actress who were game to really work the fields at a goat farm in which they might be asked to skin a rabbit and the occasional sheep castration wouldn’t be out of the question. Yet by the time Ruth Wilson and Mark Stanley made it out to Yorkshire, playing the siblings Alice and Joe Bell, respectively, who try to put aside a painful past to keep the farm afloat upon falling on hard times, the physical labor might’ve come as a relief after the mental stamina the parts required, so much so that Barnard suggested that they talk through their character motivations with psychologists.

“As I was writing the script, I was speaking to psychotherapists and I put them in touch with the same people because I found it so helpful and vital,” says Barnard. “So they had their own individual conversations with those people which they found very useful.”

It’s notable that initial funding for Barnard to begin writing “Dark River” came from a science grant rather than a film entity, as the writer/director probes the way memory works with the rigor of a neuroscientist to express what Alice is up against in returning to her family’s land after 15 years away, barely able to step foot in the house where she was frequently abused by her father (Sean Bean). While he’s since passed, the relationship between Alice and Joe remains in shambles and although her brother lives with the knowledge of what transpired without having done anything to prevent it, Alice’s trauma is even more all-consuming, seeing nothing but poisonous weeds on the acreage that she intends to sell if only she can reach a detente with Joe.

Envisioning the ravaged land as an extension of Alice’s psyche, Barnard toys with perspective in “Dark River” nearly as radically as she did in her visionary nonfiction debut “The Arbor,” in which she reflected on the life of Andrea Dunbar with actors mouthing the words of family members and friends’ remembrances that she had recorded to create an experience that allowed the words that had been so dear to the playwright come alive in dazzling fashion. With more dramatic license afforded by the fiction of Rose Tremain’s novel “Trespass,” Barnard couples a fierce performance from Wilson with an intricately crafted immersion into Alice’s way of seeing the world to show how the past constantly informs the present as certain scenes bear resemblance to one another and memories can be triggered by small details and gestures, not only for Alice, but for the audience.

Although a harrowing journey, “Dark River” nonetheless is one well worth taking due to Barnard’s artistry and compassion and following the film’s well-received run on the festival circuit that began last fall at the Toronto Film Festival, Barnard spoke to us on the of the film’s U.S. release this week, recalling how a committed cast made an arduous shoot gratifying, using sound design to express emotions and the unpredictability of goats.

Mark Stanley and Ruth Wilson in "Dark River"How did this come about?

There’s a novel by Rose Tremain called “Trespass” that was really the inspiration, which was quite a different way of working for me because usually I’m following my own impulses. But there are two sets of adult siblings in the book, and what I was really interested in was the relationship between the siblings in the book who were called Audrun and Aramon and how they were both damaged by the same set of circumstances and in a way how he is as damaged if not more damaged than she is and their need – and their inability – to connect, so I was very curious about that and wanted to explore.

When you moved away from a straight adaptation, did it feel natural to set the film in Yorkshire?

Yeah, it’s a place that I know and I love. I grew up in the middle of nowhere and when you’re a child in that environment, you’re as fascinated by a dead rabbit as much as you are by a beautiful flower or a butterfly and everything is visceral and real. You’re not looking at it at a distance like a picture postcard, so that’s what I really wanted to get a sense of was that in a way, it’s more beautiful if we engage with it in a real way rather than painting pictures or distancing ourselves from it.

And I hung out with tenant farmers quite a lot and that influenced [the film] massively, finding the veracity of the detail and really rooting it in a very specific place and very specific people’s lives. Casting the goat farm was really important, and most of the tenant farmers that I met were driving lorries because you couldn’t make a living from sheep farming alone. We found a farm that we didn’t do that much to it [to be in the film]. It’s a real working farm. [When we shot the film], the sheep were a nightmare to work with — they never do what you want them to do, but some of the shots of the sheep I like. They’ll look at you in a really weird way. [laughs]

When you’re casting actors, I imagine then it isn’t just asking who can play this brother and sister, but who’ll literally get in the mud with you. How did you get this duo?

Ruth and Mark are just extraordinary, amazing actors and their commitment was 200%… 400% [laughs] I knew that they were going to give themselves over to it completely and they did. Ruth went and spent weeks and weeks with the tenant farmers that I did my research with, getting her hands dirty, castrating lambs, doing all these disgusting things and likewise Mark did the same. They were rolling around in the mud and Ruth learned to shear sheep and Mark would scream into a pillow for 24 hours to get his voice right.

Meanwhile, we were working alongside [that preparation], workshopping stuff and going through the script and refining everything. The script had very little dialogue to begin with, but [that process] was a case of taking dialogue away and [figuring out] how to communicate what was going on for both of them inside without them being able to speak directly it, so it all had to be done through subtext and performance. It was quite a challenge, but they were just incredible in terms of their preparation and their attention to detail and their ability to be instinctive and in the moment. Mark would quite often do unpredictable things, and I’d love that, so [sometimes] we’d change the way slightly we were shooting so that we could accommodate those things he wanted to do — I didn’t know he was going to pull the table over the top of his head, for example. That was such a pleasure working with such talented, brilliant people.

Ruth Wilson in "Dark River"One of my favorite touches in the film is the sound of this plane taking off to signal the eruption that Joe has – just in general, is there a particular sensitivity you have to collecting sound on set?

I’m so pleased that you noticed. I’ve worked with a sound designer named Tim Barker for a really long time and he’s a genius. He’s also the sound recordist and I don’t think it’s probably until post that he thought that was going to work there, but I think it had been on his mind from being on the set because of these military jets that pass over the moors there. They just come out of nowhere and sound like that, so being on set recording sound is giving him ideas all the time about what might be in the sound design.

Did the weather cooperate?

The weather changed all the time — within an hour you could have sun, rain and wind, which made continuity really difficult, so it was a challenge just because it was so changeable. We shot it in June, so the nights were very, very short and we had quite a lot of stuff that we shot at night, so the schedule was tricky.

I was also really intrigued to hear how you coordinated the flashback scenes to interact with the present – what was it like to recreate similar blocking without losing the spontaneity and naturalism that you’re known for?

Yeah, that was tricky. It was very tricky and probably easier in some ways for the adult actors than for the teenage actors because I think breaking that flow becomes very technical. There was quite a lot of work to be done and in some ways, it was work that I expected [to do in the editing room] because I needed to give myself options when we were shooting. But then it was a case of taking [more and more] things away, so that it was as subtle as possible, but enough for an audience to understand what had happened in the past.

Mark Stanley in "Dark River"You open and close the film with some evocative PJ Harvey music. How did she get involved in the film?

She saw “The Selfish Giant,” and she wrote me a letter, which I was thrilled about because I’ve loved her work for a very, very long time. It was after that that we met and we talked about the possibility of working together and then I sent her the script for “Dark River.” She was really excited because she had grown up on a farm and had actually been reading all the same poems I was reading. [laughs] There was a kind of synchronicity there, so she and the composer and I all worked together with ideas about what song we thought might work at the beginning and the end of the film. This was before we shot anything and we were really coming forward with the same kinds of ideas. Then towards the end of the edit, it became clear what the song [“An Acre of Land”] could be to set things up narratively, but also thematically, and she’s got a beautiful voice, so that was a real pleasure working with her.

“Dark River” opens on June 29th in Los Angeles at the Monica Film Center and the Pasadena Playhouse and in New York at the Village East Cinemas.