Hugh Jackman says playing the role of a father to a depressed teenager in "The Son", which premieres in Venice on Wednesday, made him rethink his entire approach to parenting.
The Australian star says he had a need "like a fire in my gut" to play the part after reading the theatre version by writer-director Florian Zeller.
Jackman plays alongside Laura Dern as divorced parents trying to cope with a teenage son who is falling deeper into depression.
"It was a compulsion...it's a scary, beautiful feeling to have, that you rarely get as an actor, that you feel the part is right for you at this point in your life and you just must play it," he told reporters in Venice, where the film is competing for the top Golden Lion award.
What he didn't expect is how the film's devastating look at mental health would change his own relationship with his children.
"For many years as a parent, the job was to appear strong and dependable," he said.
"But...since this movie, I've changed my approach. I share my vulnerabilities more with my 17- and 22-year-old kids, and I see the relief when I do."
Jackman said he made the rare choice of emailing Zeller to request the part personally.
Zeller, who won a Best Screenplay Oscar for his first film "The Father", said he agreed after just eight minutes on a Zoom call with Jackman.
"I felt something very strong about the reason he was connected to that story," Zeller said.
"It was the best decision ever because from that moment it was such a joyful, truthful and intense journey that we have shared."
- 'Greatest crisis' -
Dern said the film carried a particularly vital message in the wake of the Covid-19 pandemic.
"The greatest crisis that has come through this time is the epidemic of mental health, particularly in adolescents and young adults around the world. The numbers are so shocking," she said.
Although the teenager, played by newcomer Zen McGrath, blames his parents' divorce for his difficulties, Zeller said mental health issues are "much more difficult to explain".
"My intention was not to try to explain where it comes from," he said.
"It was important for me to capture that mystery...the frustration that comes with wanting to help someone and not knowing where it comes from."
There are moments of light relief in the film, especially one featuring some dad-dancing from Jackman.
The actor said he tried to practice some embarrassing moves with his daughter, who assured him: "Dad, you don't need to rehearse."