The fourth entry in the “Mad Max” franchise may have been hailed as a masterpiece, but behind the scenes, things weren’t so brilliant.

In the new book Blood, Sweat & Chrome: The Wild and True Story of Mad Max: Fury Road, Charlize Theron and Tom Hardy open up about their difficult working relationship on the 2015 film.

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“It was like two parents in the front of the car. We were either fighting or we were icing each other — I don’t know which one is worse — and they had to deal with it in the back. It was horrible! We should not have done that; we should have been better. I can own up to that,” Theron recalls in the book, according to an excerpt published in Vanity Fair.

Actor Nicholas Hoult described the situation similarly: “It was a tense atmosphere at times. It was kind of like you’re on your summer holidays and the adults in the front of the car are arguing.”

Theron adds, “Because of my own fear, we were putting up walls to protect ourselves instead of saying to each other, ‘F**k, this is scary for you and it’s scary for me, too. Let’s be nice to each other.’ We were functioning, in a weird way, like our characters: Everything was about survival.”

One particular incident involved Hardy arriving late to set, as he had often done, despite a specific request that day to arrive at 8 a.m..

The actor finally arrived several hours late, at which point Theron was irate.

“She jumps out of the War Rig, and she starts swearing her head off at him, saying, ‘Fine the f**king c**t a hundred thousand dollars for every minute that he’s held up this crew,’ and ‘How disrespectful you are!'” camera operator Mark Goellnicht recalls. “She was right. Full rant. She screams it out. It’s so loud, it’s so windy—he might’ve heard some of it, but he charged up to her up and went, ‘What did you say to me?'”

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Goellnicht continues, “He was quite aggressive. She really felt threatened, and that was the turning point, because then she said, ‘I want someone as protection.’ She then had a producer that was assigned to be with her all the time.”

“It got to a place where it was kind of out of hand, and there was a sense that maybe sending a woman producer down could maybe equalize some of it, because I didn’t feel safe,” Theron says. “I kind of put my foot down. [Director George Miller] then said, ‘Okay, well, if [producer Denise Di Novi] comes…’ He was open to it and that kind of made me breathe a little bit, because it felt like I would have another woman understanding what I was up against.”

Miller says, “There are things that I feel disappointment with about the process. Looking back, if I had to do it again, I would probably be more mindful.”

Meanwhile, Hardy acknowledges, “In hindsight, I was in over my head in many ways. The pressure on both of us was overwhelming at times. What she needed was a better, perhaps more experienced partner in me. That’s something that can’t be faked. I’d like to think that now that I’m older and uglier, I could rise to that occasion.”