Viggo Mortensen stars as a gay man attempting to care for his ailing, conservative father in Falling

Viggo Mortensen is making his directorial debut with a deeply personal story about memory.

In a PEOPLE exclusive first look at the trailer for Falling, Mortensen stars as John, who takes in his conservative father, Willis, after he's diagnosed with dementia. Their complex relationship takes a turn as Willis' views on life clash with John's partner, Eric, and their adopted daughter, Mónica.

Mortensen, 62, tells PEOPLE the story is close to his heart after seeing his mother suffering from dementia "for several years" before her death in 2015.

"After her funeral, I wanted to remember everything I could about her, explore what I felt I'd learned from her and, by extension, from my father," he says. "Memory, I have come to believe, is more a collection of feelings than a collection of facts. What we recall is quite subjective most of the time."

Viggo Mortensen Falling

"We unconsciously edit and try to control our pasts in order to feel at ease in the present, whether we end up suffering from dementia or not," says Mortensen. 

The Oscar-nominated actor says he tapped into 40 years of acting experience to direct the film, saying, "Experience has taught me that a good idea can come from anyone at any time."

He credits his crew and his cast—which includes Terry Chen, Gabby Velis, Lance Henriksen, Sverrir Gudnason and Laura Linney—for contributing their ideas to the film.

Viggo Mortensen Falling
Viggo Mortensen Falling
Credit: Brendan Adam-Zwelling

"Happily, they brought a lot, and invested themselves personally and with great honesty in the story we were telling," says Mortensen. 

The Lord of the Rings star says he had attempted to direct a film for almost 25 years before Falling came along, saying opportunities had never panned out after he wasn't "able to raise sufficient financing to start shooting."

"Making Falling was every bit as difficult as I imagined it would be," he says. "But even more rewarding that I'd dreamed it could be. I can't wait to tell another movie story." 

 Falling is in theaters, on digital and On Demand on Feb. 5.