The Famine - it's the ground zero of Irish history, an event so traumatically cataclysmic that for a century afterwards, people barely spoke of it. That slow catalogue of lingering death and unimaginable suffering is so grim that film-makers have avoided the subject like the plague, and when director Lance Daly started shooting Black 47, he soon realised why.
"We got into week two and I was like, oh my God, what have I done? I've signed up to this and now I have to do it, but how am I going to get it finished?" His film, a swaggering epic that uses the Famine as a heart-rending backdrop to a tale of betrayal and revenge, stars Australian actor James Frecheville as Martin Feeney, an Irish Ranger who returns home to Connemara after service overseas with the British Army to discover his homestead destroyed, his family scattered or dead.
Intent on revenge, he goes in search of the landlords and judges who persecuted his kin. Meanwhile, a former British Army colleague called Hannah (Hugo Weaving) has been ordered to hunt Feeney down. It works wonderfully well, and the adventure story provides an oblique way in to the bigger story of the Famine.
"I think this was a really smart way of addressing the subject," Daly says, "and the producer Macdara Kelleher had spent a long time developing this script in various forms before I got involved.
"This is the first ever film about the Famine, isn't it? And when you think about it, maybe the genre route was the only way to go. I mean, do you want to make a film that's just about suffering, about people watching their children starve and families lying dead in their homes? Do you want to watch it, do you want to make it, do you want to be someone who tries to dramatise that? You had to tackle it in a less direct way."
Lance and his producers were determined, as much as possible, to get the details right. "From the time I signed on till when we started shooting, I read maybe seven or eight books on the Famine, but I also had an assistant who was reading, we had a military historian, a political historian, an art historian, and we had the Quinnipiac Famine Museum in Canada, which is the biggest visual archive - they have every newspaper cutting from the time, they've every image, all the paintings. So we had all that and I think we did everything we conceivably could. The historians have been very positive about it."
Like a lot of Irish people, Lance's understanding of the subject was hazy before he started researching it. "I think it's vague for everybody: we all have this basic idea that there was a dependence on the potato crop and the crop failed, that's about as far as it goes. And internationally, people say, 'Oh yeah, there was a famine in 1840-something', and there's this idea that the Paddies were all a bit thick and a bit lazy, and they depended on the spud and it backfired.
"And then in Ireland, there's this other narrative where people say there was food and they exported it and there was a genocide plot, but when you begin to delve into it, it's just so much more complicated than that. There are so many different ways to look at it, but it's great to see how fired up everybody is: if you look at the YouTube trailer for the film, the arguments after it are just endless."
Shooting the film was hard. "When we were making it, I began to wonder was it cursed because we were trying to make a movie about the Famine! I haven't actually said this to anyone before, but it really did feel like that. I got pretty beat up by the whole process, and I remember doing the last shot in Connemara, and my wife had come down, so we went to Leenane and got out of the car and the sun was going down and I actually felt this tangible weight lift off my shoulders.
"I felt like I'd been carrying this, and I don't know if it was just that the film was so hard: period detail, the weather, ensemble cast, resources, horses, action, two languages, kids - it's like all the boxes that would tell you this is going to be a tricky shoot, they were all ticked."
A strong supporting cast includes Stephen Rea, who's brilliant as a wily western peasant, Sarah Greene, Moe Dunford, Barry Keoghan and Jim Broadbent, who plays Lord Kilmichael, a liverish landlord who refers to the Gaelic tongue as "that aboriginal gibberish" and dreams of a time when "a Gaelic Irishman will be as rare a sight as a Red Indian in Manhattan".
"It was Jim who wanted his character to be completely irredeemable. I was more sympathetic and he was like, 'No, he's a total p***k', he sort of made a judgement about it, which actually worked very well in the end."
Daly was one of a new generation of filmmakers who emerged in the mid-2000s determined to move beyond the stodgy, word-heavy traditions of Irish cinema. In films like Kisses (2008), he used visual lyricism and cinematic storytelling to great effect, but before Black 47, he was at a crossroads. "I had a few years where I hadn't made a film because I wasn't sure what the right thing to do was - I'd sort of lost my way a little bit.
"Black 47 is very different from my early stuff, but it felt right. It excited me again, and I've definitely got a clear line to a couple of projects, and I've kind of found a new route I want to go in, which is action, you know, it's a lot of fun, and something that isn't really done in Irish cinema and I enjoy it. I'm really interested in the whole visual side of things as well."
Black 47, meanwhile, has already opened in Ireland, and opens in the UK and America on September 28. One imagines it should be of huge interest in the US, because there are so many people there whose stories begin with the Famine.
"It's just getting them to hear about the film that's hard - it's such a big place: it's guaranteed a hundred screens over there for its opening, though, so that's good. Everybody always goes on about the diaspora, and you hear there are 40 million Irish Americans. Well if this doesn't find that audience, given its subject, I don't know what will!"
For such a relatively young actor, Barry Keoghan has a canny knack of turning up in high-quality, interesting films. Last year the 25-year-old Dubliner played a nervous mariner in Christopher Nolan's multi-Oscar nominated war epic Dunkirk, and was unforgettably sinister as a teenager with an agenda in Yorgos Lanthimos' wonderfully weird drama The Killing of a Sacred Deer. In 2018, he's not resting on his laurels: next month he'll appear in Lance Daly's daring Famine-era saga Black 47, and will also star in American Animals, a strange and distinctive indie drama from Bart Layton.