Credit: Paramount Pictures

WARNING: The following contains spoilers for Mission: Impossible — Fallout.

It’s a good thing Tom Cruise and Mission: Impossible — Fallout director Christopher McQuarrie speak their own language.

No, really: The pair, who have collaborated on seven films (including Fallout and Rogue Nation), know how to communicate without speaking in full sentences, or even words. “We’ve developed a shorthand to where the other actors don’t really understand the language we’re speaking anymore,” McQuarrie says, laughing. “We kind of look at each other and go, ‘Yeah?’ ‘Ah!’ “Mmhmm,’ ‘Uh, right, with the thing.’ And Rebecca Ferguson is standing there going, ‘You understand that no one else knows what you’re talking about.’ But to Tom and I, it’s so completely clear.”

That shorthand helped the two pull off the franchise’s latest jaw-dropping practical stunt: a HALO (High Altitude-Low Opening) jump in the first act of the film. After all, they were the only ones who thought it could be done. “Everybody told [Tom] that it was impossible, but now I’m just accustomed to it,” McQuarrie says. “There’s always somebody willing to tell Tom Cruise, ‘Hey, you know you can’t do that. And I just look at them and go, ‘This is your first Tom Cruise movie, isn’t it?'”

Below, the director takes us through the steps to capturing the scene.

Credit: Paramount Pictures

The Challenge

It wasn’t just about jumping out of a plane at 25,000 feet. It was also about lighting, camera technique, and selling the action. (Remember: the sequence involves Ethan rescuing Henry Cavill’s August Walker mid-air.)

Then again, McQuarrie was the one who wanted to pull off the jump at dusk and in one shot. “It couldn’t be too bright, and it couldn’t be too dark, so we had an envelope of exactly three minutes of available light every day,” he explains. “If Tom didn’t get the shot, that’s it, we came back the next day and did it all over again. We got exactly one take every day. So all day we would rehearse and then at dusk, you’d have one opportunity to get the shot.”

He also needed Cruise to not only leap out of a massive military cargo plane, the C-17 Globemaster, but also act, portraying Ethan’s desperation as he tries to deliver oxygen to a reckless, passed-out Walker. “There’s a fair bit of action happening within it, and that’s what made it so complicated to shoot,” he says. “We didn’t want cuts, so you had to be able to choreograph all of this action while following it anywhere from 120 to 200 miles an hour.”

Credit: Chiabella James/Paramount Pictures

The Preparation

Even before testing jumps, the team needed to have the right suits — and more importantly, the right helmets. (If you can’t see Cruise’s face, how do you know he’s the one pulling off the stunt?) McQuarrie says a helmet was created just for the film that would light Cruise and Cavill’s faces correctly (see below), as well as — more importantly — keep Cruise alive as he did the jump. “That’s not just a prop,” McQuarrie points out. “It’s a proper life-saving device.”

A life-saving device that could have just as easily ended lives as well. The director says that as they were fitting the helmet with lights, they worried that if the lights sparked, Cruise’s head would catch on fire. To avoid that scenario, the helmets were tested at an even higher altitude of 35,000 feet. “All of it was tested very rigorously,” he explains. “The oxygen bottle, the flight suit, the parachute, all of it was scratch-built specifically for that sequence before Tom began doing his skydiving training.” He pauses, then laughs. “It was another kind of impossible.”

Credit: Chiabella James/Paramount Pictures

The Final Product

After rehearsing first with a wind machine, Cruise and McQuarrie moved on to testing actual jumps. In the end, Cruise did 105 (105!) jumps total — with camera operators around him and the Earth hurtling toward them all — in order to achieve the shot.

McQuarrie, though, hesitates to call this stunt the biggest he and Cruise have ever accomplished; after all, he was there when Cruise held onto the side of a plane, and in Fallout, he had Cruise pilot a helicopter in a fight against another helicopter. Is the HALO jump really better than them all? “It’s very difficult to say what is the quote-unquote biggest,” he muses. “They’re all complex, they’re all difficult, and they’re all extremely dangerous. All of them require specific training, and every time we did one, we kept saying, ‘This is the stunt.’ And then we’d get another!”

In fact, they wound up shooting so many dangerous sequences over the course of filming Fallout that McQuarrie admits they had to leave a stunt or two on the cutting room floor. “There was just simply too much movie,” he concedes, laughing.

At least all that effort for the HALO jump — more of which can be seen below — made it in:

Mission: Impossible — Fallout is now in theaters.