'Dune: Prophecy' star was worried she was going to fall off a cliff filming one of her most intense scenes

• 'Dune: Prophecy' star Jessica Barden filmed one of her most intense scenes at the edge of a real cliff.
• Barden plays the younger version of Valya Harkonnen, leader of the Sisterhood, on the prequel series.
• In episode three, Barden stood in the freezing rain for hours to film her big scenes.

Jessica Barden may play one of the most inscrutable characters on "Dune: Prophecy," but in real life, she's more than happy to share whatever's on her mind. And when it came time to film one of her most intense scenes, that was: Why am I doing this?

Barden plays young Valya Harkonnen, the vengeful and ambitious young woman who becomes the leader of the Sisterhood (a group that would eventually become the superhuman-powered Bene Gesserit by the time of the Denis Villeneuve "Dune" films).

She shares the role with Emily Watson, who plays an older Valya secure in her position of leadership over the group. In the flashbacks that center on Barden, though, Valya is still doggedly climbing that ladder to achieve more power, which, at one point involves standing in the freezing rain for hours.

"It was our second day of filming as well," Barden told Business Insider of the tough scene. "It was also December in Hungary."

The scene in question takes place during "Dune: Prophecy" season one, episode three. It delves into Valya and her sister Tula Harkonnen's backstories, and it's Barden's biggest episode yet. At one point, Valya and the other acolytes are standing out in the rain as a trial.

Barden said that camaraderie was the key to braving the cold during filming. "The crew was amazing. They make a hot tent, and they bring you tea, and a towel, and stuff. And when you're together it's fun, and you're just laughing like, 'Why are we doing this? This is crazy,'" Barden told BI. "But then, when you're by yourself, you're just like, 'Why am I doing this? This is crazy.'"

Once Barden was on her own, she asked episode director Richard J. Lewis not to cut filming short if he felt bad for her standing out in the cold — if she was going to do this, she wanted it to look good. Lewis agreed and even gave her the feedback that she looked "too cold" at some points and needed to tone it down.

"I'd be like, 'I'm going to kill you. I'm literally going to kill this man,'" Barden joked. "But I was really proud of myself when I did it, when it was over."

Later in the episode, Valya experiences the Spice Agony, a potentially fatal rite of passage required of all Reverend Mothers, at the edge of a cliff on the Harkonnens' home planet. Turns out, none of that landscape was CGI — they were filming on location at a real cliff at 5 a.m.

"It was a sheer drop," Barden said. "And my eyes would close, and act in this agony, and Richard would be like, 'Okay. Imagine it's going through your veins.' And the whole time I was like, 'Oh my God. I'm going to fall off the cliff.'"

The "Dune: Prophecy" season finale airs Sunday at 9 p.m. ET on HBO and streams on Max.