Autumn 1998. Beverly Hills, Los Angeles. Pitt’s tossed Norton’s stunt double down the stairs several times already.

Eventually, Fincher will use take one. Now, he’s heading for take 12.

Pitt grabs the guy and chucks him... Out, out, out, missing the first flight of steps and – CRUNCH! – slamming like meat on a chopping block, down onto the first landing.

Fincher gasps. There’s a long, long silence. The crew is waiting. The director takes his hands from his mouth and says, voice questioning, “Um, cut?”

“Fincher does all these tough things and he’s such a puss when it comes to blood and injuries,” laughs Norton.

“There’s a shot in the movie where Brad throws me through the toll booth of a parking lot and I crawl under a car. It’s an elaborate shot and Fincher wanted to do it all in one."

"So we did it a lot of times. Like a lot. Like 20 or 25 times. I remember going into a headstate of like, ‘Fuck it. I can do as many as he wants me to, because there’s no going back now.’

"Eventually Brad started getting uncomfortable, around 33 or 34, and he said, ‘Look, seriously, no more. He’s really getting beat up!’ Fincher just goes, ‘Last one, I swear! Last one!’

"So I went crawling under the car as hard as I could and I was too tired and I didn’t duck enough and I really rang my head hard against the transmission and sort of screamed and he jumps up and goes, ‘That was the one!’”

“Yeah, a lot of people got hurt,” remembers Fincher.

“We had people with dislocated fingers and broken ribs. We didn’t want burly stunt guys, we wanted them to look like scrawny prep cooks and concierges and bellmen. The great news about actors is they all, ironically, look like waiters...”

The oddest experience, though, was surely for the leads, whose injuries started mirroring each other.

“It was weird,” says Norton. “Like, I jammed my thumb really badly and then Brad jammed his thumb, and then he really took a bad shot to the ribs and he was hurt under his ribs and I remember thinking, ‘Ooh, I hope I don’t get that one!’

And then like a week later I fell on it right on my ribs. I remember walking out of the soundstage holding my ribs and Brad was like, ‘Noooo!’” It wasn’t the only parallel.

The pair did a lot of “fun things” – they learnt to make soap and, at the mischievous suggestion of Fincher, Norton hired the same truck as his co-star.

He also chose to lose weight for the role of The Narrator, while Pitt bulked up for Tyler. “Fincher and I both thought a little bit of Fight Club as like a drug metaphor,” says Norton. “The Narrator talks like a junkie. And the more The Narrator falls apart, the more in his mind Tyler is becoming more and more idealised.

I don’t remember if it was a conscious conversation between me and Brad and Fincher, but I know Brad got bigger and bigger the more the shoot went on and I got smaller and smaller and felt worse and worse and I think it just seemed right."

"It seemed like the right progression, because it takes him a long time to see that it’s not empowering him anymore, he’s turning into a bruised, scabbed skeleton and I think I tried to go as far as I could with that.”

The differences weren’t only physical, with the stars’ acting styles contrasting, too. “Edward’s strength is he always knows where he wants to be within the context of the story,” says Pitt.

“The drawback is sometimes his planning keeps it from being fresh, in theory anyways, but the guy is just so exquisitely good that he never gets in the way.

I’m the opposite, I let the day dictate what’s going to happen and so for me it’s more of a hit-and-miss. The drawback for me is when I’m missing I’m really missing, I don’t have that to fall back on.”

“Brad’s more anarchic,” says Bonham Carter. “He’s more instinctive and intuitive and playful and prepared to be extremely bad in order to release something interesting.

I think people who are willing to go off the deep-end are going to be the most exciting and unpredictable. And Ed’s got amazing facility but he’s very intellectual. But they were both really impressive.”

It was up to Fincher to juggle the different personalities and styles. “They aren’t fuckin’ puppets, you know?” he recalls.

“No matter how far you stick your hand up their asses you can’t make their lips move. A dance is two people and when you’re dancing with a camera, a dance is five people. It can be tricky.”

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