Saoirse Ronan and Paul Mescal, together at last! They've collided ...

In a parallel universe, Saoirse Ronan and Paul Mescal are eagerly chatting about their performances in Garth Davis’s cerebral science-fiction drama Foe. The Hollywood writers’ strike did for that.

“I just feel sad for the actors,” Davis, a genial Australian, tells me. “Because they’re doing some of their best work in this movie. And I just would love them to talk about it. I wish people could hear them speak. Because they’ve got a lot to say.”

I don’t doubt it. “Together at last!” isn’t quite the phrase we’re looking for. Though Mescal scored rave reviews in 2017 for playing the eponymous enigma in the Gate Theatre’s production of The Great Gatsby, he has only been a force outside Ireland’s shores since the pandemic-defining phenomenon that was the TV version of Sally Rooney’s novel Normal People. His Academy Award nod for Aftersun this year confirmed his status. Ronan is, of course, a veteran, despite being still on the right side of 30. An Oscar nomination for Atonement in 2007. Three further nods in the succeeding 12 years. She’s a phenomenon.

Anyway, collision between the nation’s two most celebrated young actors has occurred. Based on a tangled novel by Iain Reid, Foe casts Ronan and Mescal as Hen and Junior, a testy couple living in an isolated farmhouse as the world gives in to environmental decay. When a stranger turns up and tells Junior he is scheduled for a mission on an orbiting space station, the strains in their marriage begin to show. It’s partly a domestic two-hander. It’s partly a meditation on consciousness.

“I felt that we had to cast Hen first, because she’s the spiritual heart of the movie,” Davis says. “I was looking for someone that emanated this beautiful spirit and this light. I love Sersh [Saoirse] because if you look at all the characters she plays, she’s got this beautiful personality that shines through. I really wanted to feel something like that in this movie, something that was surrounded by stuff that’s dying. So once we cast her, I went and found a husband for her. Which was Paul.”

Mescal was immediately keen.

“It just struck me that these two would feel so right together. And the fact they had the Irish heritage was icing on the cake,” Davis says.

Mescal and Ronan are very much the same generation. He is 27. She is 29. In a country this size, that would usually guarantee the actors had been bumping into one another for years. The same auditions. The same pubs. All that. But they took different paths – Mescal studied at the Lir Academy, at Trinity College Dublin; Ronan learned on the job – and, crucially, by the time the Kildare man left drama school, his New York-born contemporary was already a star. So how well did they know one another?

“I think they had met once or twice, but they didn’t know each other very well,” Davis says. “They knew each other’s work. And Paul wasn’t the superhero he is now. So it was quite early days. But they had such a respect for each other. So just starting with that was really special. And then the chemistry was there.”

[ Saoirse Ronan: ‘In Ireland there was such ownership over women, physically, emotionally, spiritually, financially’ ]

Davis had some pull when he approached Ronan. His first feature, the ruthlessly moving Lion, starring Dev Patel and Nicole Kidman, scored six Oscar nominations in 2016 and dampened millions of handkerchiefs around the globe. Mary Magdalene, his follow-up, was not a financial success, but he did manage to draw terrific performances from Rooney Mara and Joaquin Phoenix as, respectively, the title character and Jesus Christ. So our two stars will have known the director was good with actors.

Mescal was shooting the offbeat musical Carmen in Davis’s home country when the offer for Foe came his way.

“My casting agent said, ‘Paul’s in Sydney, he has read the material, and he’d really love to meet you.’ So I flew to Sydney and met him for the first time. We sat in front of this cafe and spoke for hours. We were pretty much prepping character. It was almost as if he was already on the job.”

Mescal has travelled a dizzying path since Normal People pushed him above ground. He did a Rolling Stones video. His performance at the Almeida Theatre in A Streetcar Named Desire drew raves. Then there was his heartbreaking turn as a troubled dad in Aftersun. Charlotte Wells’s debut feature arrived at the Cannes film festival with little buzz. It charmed attendees and, less than a year later, he was an Oscar nominee. He could get another nomination for his role opposite Andrew Scott in Andrew Haigh’s incoming, hugely admired gay romance All of Us Strangers. All this and his role as the lead in Ridley Scott’s sequel to Gladiator.

[ Paul Mescal: ‘Movie stardom is different to fame ... It takes so much work to achieve’ ]

“He’s very curious about the cameras and where the shots are,” Davis says. “But the sides of Paul I hadn’t seen before were these more physical moments. Running in the fields. Shooting with a gun. All this stuff. And I said, ‘Man, you’d be great in the big movie like James Bond.’ And then when he was cast in Gladiator, it didn’t surprise me. Because he can do that as well.”

Mescal has those natural gifts. But he has also made the right decisions.

“Well, that’s why he’s so great – because he chooses carefully,” Davis says. “He wants to do things that mean something to him. That’s what I love about him. And so does Saoirse. They are true artists. And they’re also just beautiful human beings.”

Foe: director Garth Davis during filming

As for Ronan’s very different arc, one sensed the Irish nation watching nervously through its fingers as she embarked on follow-ups to Atonement. Could she pull off the tricky jump from juvenile to adult lead? There were troughs and furrows. Peter Jackson’s adaptation of Alice Sebold’s (subsequently controversial) novel The Lovely Bones felt like a sure winner, but it landed with a sugary squelch. Joe Wright, the director of Atonement, found her a strong action role in Hanna, but it wasn’t until Brooklyn, in 2015, that we were reassured she’d be all right. Further strong performances in Lady Bird and Little Women sealed the deal. Fans are eagerly anticipating her appearance as a Londoner sheltering from the Luftwaffe in Steve McQueen’s upcoming Blitz.

She is now at the stage where she can help get things made.

“Yes. Of course,” Davis says.

She earns good money. But brings money to the project. Those are the cold financial dynamics of the industry.

“It’s just how it works,” Davis agrees. “So I don’t think you should cast for budget. You should cast what’s best for your movie. But whatever choice you make, it will be in the realm of what you get budget-wise. That’s just the business.”

Foe: Saoirse Ronan and Paul Mescal in Garth Davis's film

He mentioned earlier that the shared “Irish heritage” was an advantage. I wondered about that. We have established that Ronan and Mescal barely knew one another before starting the project. But those cultural connections must have been a boon. They could bond over Bosco and Daniel O’Donnell and choc ices. (Okay, they’re probably too young for Bosco, but you get the idea.) That can allow a sort of artistic shorthand.

“I think it had a huge impact,” Davis says. “In the story these characters came from the same place. They got married straight out of high school. Having Ireland in the background was useful. Sense of humour, culture, nuance – all these sensitivities are built in. Yeah, I think it makes a massive difference.”

Did he get any sense of the differing philosophies the two performers bring to their work? They got to this place by contrasting routes. They have different energies.

“I don’t know anything about where they’ve come from,” Davis says. “You could tell that Saoirse has done a lot more work. She just seemed to be at ease with all the processes. And Paul is ready to go. I think they’re both equally incredible and professional on set.”

They remain conspicuous by their absence as Foe goes before a packed audience at London Film Festival. Davis is certain that, if the strike ended tomorrow, his two stars would be straight into promotional duties like mad things. Under normal circumstances…

“Nobody would be talking to me at all,” he interrupts with a very Australian chuckle.

No, we love talking to directors.

“No one talks to me. It’s fine. Ha ha!”

Not true at all. Good luck to him.

Foe is in cinemas from Friday, October 20th