Longlegs Director Breaks Down Nicolas Cage's Terrifying Transformation: He Performed a 'Disappearing Act' (Exclusive)

For the director of Longlegs, Nicolas Cage was like a godsend — or, considering he’s playing a Satanic serial killer, a gift from hell. 

“In a business where most of the time you get kicked in the neck and people say, ‘No,’ ” Osgood “Oz” Perkins tells PEOPLE, “every once in a while, Nicolas Cage reads your script and says, ‘I'd love this and I want to do this.’ ”

Perkins, 50, calls the Leaving Las Vegas Oscar winner “quick and so diligent. He knows every movie, remembers every performance, knows every song lyric, is just a machine that way. I don't think people fully know how truly brilliant, in terms of intelligence, Nicolas Cage is.”

That became apparent early in the process of crafting Cage’s titular character. “He didn't want to improvise,” reveals Perkins. “I said, ‘You can say whatever you want.’ He said, ‘No, no, no. I just want to say what you've written. I don't want to change anything.’ ”

The writer-director initially began Longlegs as an exercise in riffing off 1991’s The Silence of the Lambs, he tells PEOPLE. Maika Monroe would play the FBI agent reminiscent of Jodie Foster’s Clarice Starling, with Cage signing on as the serial killer, not unlike Anthony Hopkins’ Hannibal Lecter, who she’s hunting. 

“The character of Longlegs was a character that I had imagined in other scenarios. He had tried to kind of nose his way into other projects,” recalls Perkins, who envisioned his movie’s villain as “a pathetic-ish guy who kind of comes to your kid's birthday party, sort of a clown, but not really.”

Bit by bit, Perkins, Cage, special makeup effects artist Harlow MacFarlane and Vancouver, Canada-based makeup effects company Amazing Ape began sculpting the character. In Longlegs’ case that even meant literal “sculpture,” Perkins says. “We'd just written on the page that [Longlegs had] bad, cheap plastic surgery.”

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Cage, he adds, “really wanted to do a disappearing act. He really wanted to go under prosthetics, which he hadn't really done, I don't think, in any movie before.”

Then came playing with his creepy-crawly mannerisms and singsong voice. Perkins and Cage remained on the same wavelength throughout pre-production, says the filmmaker. “I’d say something as oblique and out of left field as, ‘Nic, I think it's T. Rex. I think Marc Bolan and T. Rex are part of this movie.’ And he said, ‘Well, that's crazy. I was just teaching my son, who's learning to play the guitar, this backward guitar solo from [T. Rex song] 'Cosmic Dancer' on Electric Warrior.’ ”

The result is one of cinema’s most grotesque and anxiety-inducing villains in recent memory, a character with less screen time than he seems to have thanks to his sheer, unsettling menace. Perkins keeps Longlegs’ face obscured or just out of frame until late in the movie — a trick that also inspired distributor Neon to withhold glimpses of Cage in marketing materials.

"It's the equivalent of putting a warning label on a jar of nitroglycerin," Cage told Entertainment Weekly of the conceit. "The monster is a highly, highly dangerous substance. The way it's moved, unveiled, deployed has to be treated very carefully. Forget about the movie theater blowing up; the whole city could blow up, nay the country, maybe even the world."

The actor added that his mother, the late Joy Vogelsang, who struggled with schizophrenia and depression, was another ingredient in crafting the character. "I was coming at it from, what exactly was it that drove my mother insane?" Cage said. "It was a deeply personal kind of performance for me because I grew up trying to cope with what she was going through.”

Longlegs, which costars Blair Underwood, Alicia Witt and Kiernan Shipka, is in theaters now.