Anyone who has seen Michael Inside, Frank Berry’s stunning, emotional and gritty tale of class and incarceration in Ireland, would not be blamed for finding Moe Dunford somewhat intimidating. In Michael Inside, Dunford, also known for his roles in Vikings, Handsome Devil and Patrick’s Day, plays David, a hulking and feared prisoner who becomes a terrifying force in the life of Michael (Dafhyd Flynn), a naïve 18-year-old who is sent to prison for three months. Like many of his roles, Dunford embodies a breathcatching volatility, veering from protective and paternal to utterly vicious.

The fear Dunford can evoke onscreen is a testament to his acting skills, as in person he’s warm, thoughtful, and naturally good-humoured. Chatting to him in Ryan’s in Parkgate Street, he knows all the bartenders by name, and occasionally draws them into our interview as character witnesses. “Lads, do I have any time to have fun?” he calls to them, when I remark on his busy schedule.

“Jesus no, he’s a very busy man,” says our bartender with a conspiratorial wink. “He’s never here. What’s your name, again?” However, any time off he spends in Ryan’s is well deserved. Dunford has six movies out this year, including Michael Inside, Brian O’Malley’s horror film The Lodgers, and Lance Daly’s Famine film Black 47. He’s also mourning a death – his own. Earlier this year, Irish fans of global TV hit Vikings saw his character, Aethelwulf, meet a shock demise after more than four years on the series.

“I was expecting to find out reading the script, like everyone does,” Dunford says. “But the reality is that two of our producers, Morgan O’Sullivan and Keith Thompson, who are two gents, go around to the cast about these things. Keith has a name attached to him now, he’s ‘The Angel Of Death’. He’s a lovely gentleman, would do anything for you, but he’s the one who sits you down and says, ‘So we’ve had a lovely time with you, however your time has come!’ And then he’ll elaborate and tell you the fictitious way you die. And when he and Morgan told me my character was going to die of a bee-sting, I thought they said ‘a basting’ – which I didn’t think I deserved at all!”

Did he wish that he died in a more dramatic way?

“Cast members were asking me that, too,” he remarks. “But what is a good way to go? Why does a death have to be big and violent for it to matter? What matters more to me is that I got to see that character develop. He became more of family man, he took in a son who wasn’t his, so I loved seeing that trajectory.”

Dunford was told two months in advance of Aethelwulf’s death, which gave him a while to grieve not just the character, but also the impending end of his experience on Vikings, which was four years of his life “If I didn’t do Vikings, I wouldn’t be where I am now,” he asserts. “It built something up, it allowed me to grow into being an actor. It helped that it was a big show with Irish cast and crew, and I could be close to home and my family. But it was also about getting used to the grandness of it, and being there for so long got me used to working on such a big production. It also helped me get in touch with my Waterford roots, the history of it. Vikings weren’t cool back in the day or whatever, but I feel like the show has done what Game Of Thrones has done for Northern Ireland. There’s a whole Viking Triangle down there and a Viking Festival, and at Christmas I was asked to unveil the world’s longest wooden sword sculpture – it was just a sign that the community was connecting with Vikings and welcoming you, it meant a lot.”

But then, Dunford’s career has always been marked by fascinating explorations of Irish identity, and societal issues. In John Butler’s dramedy Handsome Devil, he played a homophobic rugby coach, allowing the audience to examine Irish attitudes towards homosexuality, toxic masculinity and sports culture – issues that seem all the more prevalent in the wake of the Belfast rape trial. In Terry McMahon’s Patricks Day, Dunford’s character had schizophrenia, but was also trying to have a romantic and sexual relationship, challenging the often infantilising narratives of mental health in this country – when we discuss mental health at all, that is. Now, Michael Inside addresses class, masculinity and how the justice system can force young men from certain backgrounds into a cycle of crime and incarceration.

“I count myself grateful to work on stories that are about something,” says Dunford modestly. “It’s what I always dreamed of, in a way. It’s only acting, but I enjoy it. It means a lot to get to do it.” Dunford is a huge fan of people who speak out about societal issues, such as Blindboy Boatclub from the Rubberbandits, who has essentially become Ireland’s court jester, speaking truth to power from behind a comedic mask. Dunford expresses huge admiration for the way Blindboy has normalised conversations about mental health and masculinity, openly discussing what it means to be a man in modern society.

Michael Inside will undoubtedly inspire similar conversations, and rightfully so. Director Frank Berry spent 18 months researching the film with Pathways, a prison rehabilitation service, to ensure that it was authentic to the experiences of men in prison, and the circumstances that led them there. Dafhyd Flynn gives a stunning performance as the titular lead character, who succumbs to peer pressure by taking joyrides and stashing drugs for his friends. But it’s clear that his working class background, his lack of family support, and the perception of young men in his area also rob him of leniency or opportunities.

The film is never didactic, but naturally raises questions and criticisms about who our justice system targets and who is forgiven – criticisms that Dunford was already familiar with.

“My father was a counsellor in a prison for a short time,” he reveals. “He was a counsellor for many years, but he didn’t really like the prison environment. My Dad’s a very empathetic man, he really cares about people and I don’t think he’d agree with how the prison system is run.” Due to Dunford’s awareness of these issues, he really felt under immense pressure to deliver a performance that was both representative and respectful.

“I had fears about it,” he admits, “because it’s so monstrous in its scope of the societal issues it’s addressing, and the experiences were quite far from my own. I had quite a nice childhood, I was brought up in a good place. And I read this, and there’s so much humanity in Frank’s work, which comes from his research, it’s so authentic. But it’s a tough watch, and it was a tough read.

“So I was nervous, I was nervous of making sure I didn’t just play my character as a monster, because the film isn’t about monsters, it’s about real people. It’s about the real guys, the real fathers who are in there, and their circumstances. So I was more nervous doing Michael Inside than anything else I’ve done. But whatever hope that people do or do not get from it, I think it’s a really powerful piece to watch, and it was definitely a powerful working experience.”

Michael Inside is in cinemas now.