Supernova, from writer-director Harry Macqueen, will have its world premiere next week at the San Sebastian Film Festival in Spain.

The film stars Colin Firth and Stanley Tucci as a committed gay couple struggling with a diagnosis that threatens to rip apart their relationship.

Firth, 60, and Tucci, 59, play Sam and Tusker, respectively, a middle-aged gay couple who take a road trip through England's Lake District as they digest Tusker's diagnosis with young-onset dementia.

In an interview with Deadline, both actors said that the film was about the love the characters share, not their sexuality.

“It’s the simple fact of it being two people who love each other, and it’s coming to an end, and the fear of losing the person you love,” Firth said. “It’s just these two people, but the setting being the backdrop of the Lake District with its beautiful emptiness and vast space contrasted with this tiny space they live in the van. It’s just the two of them and it’s all down to one person’s feelings for another. For all the considerations and controversies that might surround the issues that the film addresses, in the end so many of those issues are about love, and that’s what the entire focus of this film is.”

“I don’t think I’ve seen anything where it’s just about two people who love one another, and they happen to be gay,” Tucci said. “Really, the story is about love, and love is love. That’s it. It doesn’t matter if you’re gay, straight, whatever. Real love is all the same.”

The men said that their 20-year off-screen friendship aided their performances.

Firth's portrayal of George Falconer, a middle-aged professor struggling with the loss of his longtime lover, in Tom Ford's A Single Man earned him an Oscar nomination. He also played a gay character in the 2008 musical Mamma Mia!

Supernova premieres on September 23 at the San Sebastian Film Festival. A U.S. premiere date has not been announced.