Johnny Barrington has never skydived, but the Scottish writer/director of Silent Roar is wondering if the experience might be similar to how he’s currently feeling about his debut feature opening this year’s Edinburgh International Film Festival. “I’m really excited about letting it be seen by the public,” he says. “And then a bit scared and thrilled at the same time. It’s quite a good combination of feelings, but, you know, maybe it’s a bit what it’s like before you do a parachute jump.”

Speaking via Zoom from his flat in Glasgow, Barrington’s trepidations are understandable. His debut feature has, after all, been a long time coming, more than a decade on, in fact, from his award-winning short film Tumult, a violent Norse fantasy with a deliciously funny twist that played Sundance and earned him a BAFTA nomination. Backed by Skye-based producer Chris Young, then riding the wave of The Inbetweeners Movie’s incredible box-office success, Tumult made Barrington a filmmaker to watch. Then came, well, then came nothing. Until now.

“I'm an eternally tumescent supernova,” says Barrington, shrugging off the incremental progress of his filmmaking career to date. “What do you do? What do you say? You try and make films, and you write the script for the film that you want to make. But there's the boggy marshlands of development and it’s a long swamp to cross.”

Louis McCartney stars in the new Scottish feature film Silent Roar. Picture: Ali Tollervey

Getting into film after studying photography, Barrington, who grew up on Skye, spent these swamp years working as an architectural photographer, doing joinery and building houses. “I had a lot of fun going through that marshland, but you have to do other things to keep yourself sane and actually give yourself life experiences to make whatever you're writing about worth telling.”

Some of the scripts he tried to get off the ground reflected his formative influences, mainly David Lynch, Lars von Trier “and Highlander”. But Silent Roar, which is once again produced by Young, came out of personal tragedy. “The sudden death of my own father was really the catalyst. That sort of threw me into a state of, ‘Oh, I'm no longer young’, and I was really interested in how, after my dad died, because it was so sudden and unexpected, how I took a long time to come to terms with it and accept that he’d died.”

The shock of it caused him to see what he describes as “psychic phantoms” while walking around Glasgow. “Whenever I was on a busy street, if I ever saw any kind of man from behind who resembled my father in physique or taste in clothing, I'd often think that I was seeing my father and would want to look at his face. I think your brain is very attached to patterns. And so it was my brain wanting that person to be my father.”

This all found its way into Silent Roar, albeit it unusual ways. Set on the Isle of Lewis and revolving around a teenage surfer returning to school after losing his fisherman father, the film takes a cockeyed view of the grieving process as its oddball protagonist, Dondo (newcomer Louis McCartney), undergoes a strange religious awakening. Refusing to believe his dad is really dead, he finds a father figure of sorts in a creepy local priest, then starts communing with a trio of imaginary “cosmic surfers” and, at one point, conjures up a character called Swiss Jesus, who, as the name implies, is a manifestation of Christ, but one who claims to come from Switzerland, speaks with an American accent and is played by Sex Education star Chinenye Ezeudu.

Actor Louis McCartney, producer Chris Young, actor Ella Lily Hyland and writer-director Johnny Barrington on the Isle of Lewis to film Silent Roar

Barrington explains this baffling melange in terms of his young protagonist being a kind of galumphing goofball who has grown up in an irreligious family and now finds himself thoroughly untethered by grief, searching for answers about the universe, and too naive to really know yet which big ideas are worth pursuing and which aren’t. “I don’t know if this comes through in the film or not,” he confesses. “There's so much background thought, so much going on in the writing of the script."

The other big influence was "finding surfing, getting into surfing and the ecstasy of surfing. I like a lot of different sports, but I don't know any other sport that puts a smile on your face so quickly and washes away any of your on-land concerns and worries.”

He credits Australian surf cinematographer John Frank with capturing the film’s more abstract approach to the sport. Don’t expect the sort of magisterial sequences found in genre classics Big Wednesday and Point Break. Here, the camera plunges us into the swells and under the water, reflecting some of Dondo’s inner turmoil and confusion. “He was very comfortable getting as close as possible to the waves with a load of actors, some of whom couldn't surf to save themselves,” says Barrington. “It was hilariously frustrating at times, but then again, what do you expect if you try and make a film at sea, off the west coast of Lewis?”

Quite what the island’s residents will make of Silent Roar is another matter. “I’ve no interest in seeing this film as a representation of life on Lewis,” says Barrington, who treats some aspects of its religious traditions, especially psalm singing, with genuine reverence, and others with the puerile humour of a high school comedy. The latter comes to the fore via Dondo’s cool-girl classmate Sas (rising star Ella Lily Hyland), a diligent student rebelling against her own religious upbringing by challenging Dondo’s newfound beliefs with provocative questions about whether or not he thinks God has a penis. “I just thought that would be fun,” says Barrington. “All major religions are phallocentric. No matter how much you can be trying to discuss metaphysics and profound truth and the meaning of life, it always ends up being about tits, willies and fannies.”

Silent Roar screens at the Edinburgh International Film Festival on 18 & 19 August

Edinburgh Film Festival preview: Johnny Barrington on his Lewis-set surf movie Silent Roar