Now available, finally, is Falling, the first film written and directed by Mortensen, a theater and movie actor, published poet, musician, photographer and painter.

Falling tells the story of John Peterson (Mortensen, in more of a supporting role), a middle-aged gay man living with his partner Eric (Terry Chen) and their daughter Monica (Gabby Velis).

John sees that his father, Willis (Lance Henriksen), is showing signs of dementia and is unable to look after himself on the isolated farm in the north-east of the United States where John grew up. Some might say Willis, a cantankerous and aggressive man with views to offend many, doesn't deserve help and care.

But when Willis can't look after himself any more, John tries to convince the old man to join him in California.

After its premiere at Sundance in January last year, Falling is streaming, nearly two years later. This interview is based on a phone interview that took place in March.

Falling was well received at the Lumiere Festival and invited to Cannes.

"Then all the things that were supposed to happen, didn't," Mortensen recalls.

Still, the film has picked up a best film award at San Sebastien, and there have been multiple nominations for the performances, cinematography, editing and costume and art design - all testimony to the collaborative production of which Mortensen is clearly proud.

"I said to members of my team on the first day of shooting, 'Let's tell this movie together'."

The collaborations with the actors, cinematographer Marcel Zyskind and editor Ronald Sanders have brought about wonderful results in this intimate portrait of the relationship between father and son, told from different perspectives that drift across the sands of memory.

It was a brisk five-week shoot in which Mortensen elicited sensitive and persuasive performances from his actors, including the children.

The film reflects the range of artistic sensibilities of Mortensen, who is also a poet and musician. It's his music we hear on the soundtrack.

It's beautifully assembled and very fluent, I say. It must have been quite a challenge shaping the various points of view into a coherent narrative.

"Yeah, it was a bit of a jigsaw puzzle. Going back and forth in time and all the storylines, but I liked the challenge."

Was it a painful experience, writing it and revisiting the experiences that prompted you to make the film in the first place?

"Shooting it?"

No, writing it. Revisiting the experiences that brought it about.

"You know, the story's a fiction. There are some elements based on memories from my early childhood, and the dynamic between the parents and the past was somewhat similar, but it's different.

"I'd say it's 90 per cent fictional. I'm one of three brothers, I don't have a sister. But there are certain elements, yes," Mortensen says.

"I didn't know what I intended it to be, I just started writing after my mom's funeral. At the time of her death, the memories were very vivid. I wanted to remember her, to keep her memory alive, and then I started exploring something else. Falling has as much to do with my father now. It was in a way revelatory."

In Falling, the mother figure, Sarah, is played by Canadian actress Hannah Gross. Sarah is a person who is, Mortensen says, "in a way, the conscience of the story" with her two adult children, John and sister Gwen, who want to protect her memory.

"It really drives them crazy, when Willis confuses her with his second wife."

Inevitably, perhaps, Willis Peterson, a patriarch from another time and place who dominates all around him, becomes the centre of the story. Sverrir Gudnason and Henriksen are both splendid in their respective roles as the younger and older Willis.

Henriksen is abrasive and Gudnason, playing Willis from his 20s to his 40s, is also particularly good.

Anthony Hopkins' elderly character suffering dementia in The Father has nothing on Willis. Willis is a bundle of outrageously racist, homophobic and sexist views that alienate him from many.

During the Q&As Mortensen did in Europe, the writer-director became aware of a polarisation between generations in the US that seemed to be everywhere.

"It doesn't really matter if it's the divide between right/left, or gay/straight, or black/white, it's the inability to communicate at all that is the problem. If you can argue then at least you're talking," Mortensen says.

"The internet should have been a great means to connect us to see that we're not so different, when actually it has become a tool to find out more information that suits our purposes."

How did Willis become such an angry bigot? Was that the mystery that Mortensen wanted to unlock?

"Well, I don't think a movie profits by trying to explain every single thing. In fact, I like movies that invite you in ... by virtue of their qualities, to take part in the storytelling."

Indeed, Falling maintains a subtle ambiguity, avoiding giving answers to questions like the detonating incident that made Willis and Gwen split up.

"People in the US may say that Willis is too extreme, that there aren't people like that ... Well, there are a lot of people like that. It's a generalisation, that men of that generation, many of them, if they weren't that way, were under pressure to be that way. The head of the house, the final arbiter about everything. It was a man's role and Willis was part of that. He's not such a freak, really."

As a result of dementia in Mortensen's family, the filmmaker has been caregiver on more than one occasion. His character John is all patience and forbearance.

"That was part of it but it was also a practical thing. He also wants to help, and if he doesn't help this guy, a mean bastard, then who will? Willis may not even accept help from anybody else."

There is the odd moment when Falling steps away from its serious themes. We hear Hank Snow's rendition of I've Been Everywhere. Originally written by an Australian, it became a country music hit in the US for Snow.

Why did it get a run?

"Willis has been nowhere, and he doesn't care to go anywhere. He has his big farm, his kingdom. And while he's alone he can watch western movies and play his country music as loud as he wants."

It's another side of the man to appreciate in a sensitive and complex film.