In 2017, "Game of Thrones" set a world record for the most stunt performers on fire in one shot, during their season seven "Loot Train" scene.

Daenerys Targaryen and Drogon can't take all the credit. Stunt coordinator Rowley Irlam and his team set 20 stunt people on fire for a single shot. A total of 73 stunt performers were set on fire throughout the scene.

But how do stunt people actually get set on fire? Doesn't it hurt? We talked with Irlam to find out what it takes to safely set someone on fire.

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Following is a transcript of the video.

Rowley Irlam: Action!

Narrator: Last year, "Game of Thrones" set a world record for the most stunt people on fire in one shot. And it looks like it hurt. A lot. Can't Hollywood just use CGI? Each year, dozens of movies and TV shows feature scenes where stunt performers are set on fire. It turns out, this is often done with real fire, not visual effects. Fire and water are some of the hardest things to create in CGI. And stunt performers bring a unique take to each scene.

Rowley Irlam: What you still get from a person that you won't get from VFX is a human performance and their own take on something.

Narrator: That's stunt coordinator Rowley Irlam. He's worked on films like "Guardians of the Galaxy" and "Harry Potter and the Deathly Hallows." His latest project has been the last four seasons of "Game of Thrones." Sounds easy, right? Get a few stunt people, some fire, and your scene will look great! Turns out, even just a few seconds of fire requires a lot of work. You're not just setting people on fire, you have to set them on fire safely. The most extreme type of burn is one where the stunt person is fully engulfed in flame. But the biggest risk isn't burning their skin.

Rowley Irlam: You need to be holding your breath, so you don't breathe in any kind of flame.

Narrator: In order to keep stunt performers safe, Rowley and his team count out loud to let them know how much time is left.

Rowley Irlam: 11! 12! Out, out, out!

Narrator: They remain on fire for no more than 15 seconds.

Rowley Irlam: The danger is disorientation, or if you were to injure yourself or bang into something, you know. What you don't want to do is breathe in because of a shock of pain or injury.

Narrator: Stunt coordinators try to anticipate and eliminate anything that could go wrong or cause an injury. Everything is rehearsed multiple times, so everyone knows where to go and what to do.

Rowley Irlam: If you do enough of it, you become competent and confident. We run a very controlled set, you know, we make a plan, and we stick to the plan, and we execute the plan.

Narrator: In addition to lots of rehearsal, stunt performers wear a ton of protective gear. And their secret ingredient is a flame-retardant material called Zel Jel. For "Game of Thrones," stunt performers wear three layers of fireproof underwear, which is soaked in Zel Jel. Above that is a rain suit to prevent the gel from being absorbed by the other layers. Next is a fire suit and a thin cotton suit. Any exposed skin is also coated in Zel Jel. Finally, their costume goes on top.

Rowley Irlam: You are now ready to be set on fire.

Narrator: And Rowley Irlam is no stranger to setting people on fire. For season seven of "Game of Thrones," 20 stunt performers were set ablaze at a single time, and 73 were lit on fire throughout the course of the scene. Each performer has their own safety partner, who helps them get dressed and extinguishes their fire. For every four safety people, there is an additional safety person. That's more than 45 crew members for just one stunt. It took weeks of pre-production and multiple cameras to shoot. But the key to making that scene convincing wasn't the fire. It was the acting.

Rowley Irlam: What we wanted to do is find the humanity of the situation. These are the human moments when you feel their suffering.

Narrator: Crafting a scene that looks realistic while maintaining strict safety standards isn't easy.

Rowley Irlam: Well, the challenging thing is to make sure that you don't make a mistake. If we can get through stuff and make it look really, really exciting and dynamic and not hurt anybody, then we've won. When we were planning to do the 20-man burn, it was going to rain on Monday. And I was like, "Well, it's sunny now." And they were like, "Okay, what do you mean?" I said, "Well, let's do this afternoon then." And he was like, "But we can't!" And I was like, "Well, why?" And he went, "I don't know."

EDITOR'S NOTE: This video was originally published on October 17, 2018.