Dakota Johnson and Sean Penn Dish on Their Unexpected Friendship and New Film 'Daddio' (Exclusive)

Dakota Johnson and Sean Penn star in 'Daddio,' a drama making its debut on June 28.

Like their characters in Daddio, Dakota Johnson and Sean Penn make an unlikely duo.

The two sat down with ET's Kevin Frazier in Los Angeles to chat about their upcoming film and unexpected friendship. The neighbors' bond began after Johnson, 34, went to Penn's house to recruit him for Daddio. After they went for a walk and talked about it, Penn, 63, agreed to co-star, then their filming and friendship started.

"She's very special," Penn said of Johnson. "Making the movie, going to work was like if you'd never heard the song 'Yesterday' before and Paul McCartney was in the back seat at work and he would play it for you, but it's a woman and it's her and you get to hear that and see those eyes in the scene. That is what it was like. That's who she's like. She's like this beautiful song and it's really nice to be around."

Dakota Johnson and Sean Penn attend the 'Daddio' premiere during the 2023 Toronto International Film Festival at TIFF Bell Lightbox on Sept. 10 in Toronto, Ontario. - Frazer Harrison/Getty Images

Writer-director Christy Hall's feature directorial debut was originally conceived as a stage play, which makes sense given the relatively simple plot of Daddio. The drama follows a woman (Johnson) taking a cab ride from JFK airport back to her apartment in Manhattan. Along the way, she engages in a conversation with the taxi driver (Penn) about the important relationships in their lives.

Johnson is grateful for the "random" friendship she developed with Penn during Daddio, which was shot chronologically in 16 days, with only two days shot outside of the car on location. She said she and Penn worked a lot but still managed to hang out "quite a bit."

"I got to get her away from that singer boy," Penn joked, alluding to Johnson's private relationship with Coldplay frontman Chris Martin. "Got to have her to myself in that cab."

At first, Johnson was nervous to show Penn the script but luckily he loved it.

"He really loved the script which I was relieved about," Johnson said. "You know, it's embarrassing when you send, which it happens to me all the time, but when you send something that you think is good to someone that you admire and they're like, 'not for me,' but luckily this was for him."

She continued, "So, it was inspiring and we really connected on it and it's also a film that talks about some difficult issues between men and women of all different dynamics and I think Sean, you know, a lot of our conversation was like, 'How do we approach that honestly but safely?' And I think one of the things was that you felt very safe in that role because it was made completely by women."

Dakota Johnson, Sean Penn and Christy Hall at the 'Daddio' screening at the 48th Annual Toronto International Film Festival held at the TIFF Bell Lightbox on Sept. 10 in Toronto, Canada. - Michael Buckner/Variety via Getty Images

At its core, Daddio is about human connection -- which is what Johnson and Penn found while filming.

Sean called the script "a gift" and "beautifully written." He said being in his 60s is pretty good when a project like this one comes along. He added that there is little personality left in the culture of arts but this had something different. Johnson agreed that the depth of Daddio is what drew her to the project.

"I think the way that [Hall] wrote this script and it has such a flow to it and all of the pauses are very intentional and all of the moments where you feel like you have a little break from the intensity of the conversation are very intentional, so that you feel like you are also on this journey with these people," Johnson said. "I love all different genres of film, but I do miss films and stories about human connection and the messiness of being a human being and having relationships with other human beings."

She continued, "I'm inspired by that on screen, on the page, in art, I'm-, that's what really makes my heart beat. So, I guess with this specific project, it just felt like it did feel like a gift, you know? And because it was so contained, and it was such a small production, it just feels like a little pocket of humanity."

Penn noted his favorite of Johnson's movies is 2019's Our Friend. As for Johnson's favorite Penn film, she'd have to say Daddio.

"Sean is the best actor. I mean, it's hard to say a favorite film of his because I got to watch him do it in real life so I would say Daddio because I saw everything that is possible," she said. "The tiniest flicker of a sparkle in an eyeball. Like, things that you know like the twitch of his face or a moment before he would start a scene, just work that is so profound and so unique to him and only his and very internal. It was like a real, a real honor."

Both Penn and Johnson said they would be happy to work on another project together in the future.

Daddio releases in theaters on June 28. Watch the trailer below. 

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