Colin Firth and Stanley Tucci's bond shines through in Supernova

Colin Firth and Stanley Tucci face up to the realities of dementia in the drama Supernova. Photo / Supplied

Old friends Colin Firth and Stanley Tucci tackle the difficult subject of early-onset dementia in Supernova. By Russell Baillie.

Reading Harry Macqueen's script for Supernova, a love story about a gay couple with one facing early-onset dementia, Stanley Tucci knew he wanted one of the roles. He also knew who he wanted in the other.

So, when he met the young English writer-director, Tucci asked whether he had considered Colin Firth. Would it be okay to show the script to him?

"Of course, I said, 'That would be amazing, thanks very much,'" Macqueen remembers. "And Stanley said, 'Good, because I gave it to him yesterday, and he read it and loves it and he wants to meet you.'"

And so Macqueen, with one modest DIY feature, Hinterland, to his name, found himself with two vastly experienced and award-winning actors, who just happened to be best mates, wanting to be in his second.

No, he tells the Listener, they didn't have to audition and, no, there was no test of the pair's screen chemistry together, as can often happen when casting romantic leads. They'd been friends since playing Nazis together in the 2001 Holocaust drama Conspiracy. In Supernova, they are Tusker (Tucci), the UK-resident American novelist with the grim diagnosis, and Sam (Firth), his English concert-pianist partner.

The couple head to the scenic wonders of the Lake District by campervan, visiting family and friends along the way while pondering and arguing between themselves about what comes next. The actors' performances under Macqueen's light touch make Supernova an affecting, elegant film.

"Stanley and Colin are thick as thieves," says Macqueen from his hometown of Leiceister, where he's visiting his mum. "They really love each other's company. They've been through so much together – not great stuff and really beautiful stuff, too. You can't really buy that. Of course, the characters are nothing like them in the flesh and the relationship in the film is nothing like their relationship in real life. But there's a depth of trust and understanding there that's lovely."

Macqueen encountered two cases of early-onset dementia in 2015.One was a work colleague who, having been fired from her job for poor performance before her diagnosis, was dead six months later. Another was a friend who had to put a 60-year-old father into care.

Initially, Macqueen, a jobbing actor, started volunteering with dementia organisations before considering putting what he had learnt into a script. Working at the University College London's Dementia Research Centre for a couple of years gave him the story grounding he needed. "It was essential to have done that. I think when you're making work about really important human issues that affect a lot of people, it's a priority to get it right for those people.

"I was really struck by how dementia affects love and relationships and I've seen films about dementia, or, indeed, terminal illnesses, that were solely focused on the person who was ill. But it was the collateral damage of that illness that interested me."

Early drafts had a straight married couple "largely because I'd met only hetero­sexual couples during my research.

"So that was my frame of reference, but it struck me that what we were dealing with were really universal things – love and death and trust.

"And they supersede sexuality, of course. Also, I'd never seen a film about same-sex love at that stage of life. So, it felt like an original and, hopefully, important thing to do."

Both straight actors had played gay roles previously – Tucci many times, while Firth got his first Oscar nomination for A Single Man in 2010, before winning the following year for The King's Speech.

Macqueen thought making a road movie where the pair are sometimes dwarfed by the vast landscape – and where they can contemplate the night sky through Tusker's telescope – would help make this otherwise intimate story cinematic.

"This film could have existed in a normal domestic setting in their house or their flat, but I just wasn't interested in telling that story. I'd seen it before. There's a version of the film that is really quintessentially English and cosy and a bit twee, maybe. It didn't seem appropriate for this kind of film."

As for his two actors, who were perhaps more used to the comforts of larger productions, Macqueen says they seemed to enjoy a return to the basics.

"The resolutely independent set-up that we had appealed to them because they usually do much, much bigger projects than this. So, in a way, they've come back to their roots to a small project but with a lot of heart. I think they felt it was an honourable thing to do."

Macqueen did make some extra demands of his stars. He wanted a scene of Firth's Sam playing the piano – Elgar's Salut d'Amour – without the need to fake it.

"And Colin, bless him, said, 'Look, I haven't played piano for a long time, but I used to play when I was younger', and then he just went off and learnt it.

"So, on the final day of the shoot, Colin just walked on stage in front of an audience of a hundred people, sat down and played it. It was amazing.

"It's fair to say that the experience of making the film could have been completely different because if you're working with actors of that calibre and you're as inexperienced as I am, I imagine it could go very, very differently and you could have had the most awful time.

"But they taught me as much as I taught them."

Supernova is in cinemas now.