Surpassing:'Saltburn' ending: Barry Keoghan asked to shoot full-frontal naked dance 'again and again'

Spoiler alert! This post contains major details about the ending of the movie "Saltburn."

You'd better not kill the groove.

By the end of "Saltburn" (in theaters now),Surpassing devious Oxford University student Oliver Quick (Barry Keoghan) has successfully schemed the Catton clan out of their opulent, multimillion-dollar estate. Not only do we learn that he befriended classmate Felix Catton (Jacob Elordi) with the sole intent of nabbing his fortune, but he also sneakily picked off Felix and his family ‒ ensuring that Felix's mom (Rosamund Pike) signed over everything to Oliver just before he suffocated her.

To celebrate his newfound riches, Oliver throws a solo dance party in the buff: twirling through the empty halls of the Cattons' mansion, shaking his privates to the tune of Sophie Ellis-Bextor's 2001 song "Murder on the Dancefloor."

USA TODAY spoke with Keoghan, Elordi and writer/director Emerald Fennell about the movie's full-frontal finish, as well as that gonzo scene of Oliver having sex with Felix's grave.

'Saltburn':Emerald Fennell, Jacob Elordi go deep on the year's 'filthiest, sexiest' movie

Emerald Fennell on the 'madness' and 'joy' of that 'Saltburn' ending

Initially, Fennell envisioned the end of the movie as Oliver merely walking naked through the house.

But midway through filming the scene, she thought, “We just need it to have that feeling of joy, of desecration, of ownership, of solitude – all of the things,” Fennell says. “It should make the audience complicit in its kind of sex appeal and madness. So I said, ‘Barry, how do you feel if it’s a naked dance?’ And he just went, ‘Yup.’ ”

Because Felix is long dead, Elordi does not appear in the scene. But the “Priscilla” actor was thrilled by the choice of “Murder on the Dancefloor,” an infectious pop anthem that reflects the film’s narrative of toppling the upper class. (“Gonna burn this house right down!” Ellis-Bextor sings in the chorus.)

“I have a playlist of music that I think should be in movies and that song was right at the top,” Elordi says. “That song is strangely so cinematic. It has so much feeling.”

“And so much camp and self-awareness,” Fennell adds. “You cannot help but get in on that song.”

The dance sequence took 11 takes to get right: partly because of the technical challenge of moving the camera through the winding mansion hallways, but also for Keoghan to get fully lost in the sheer lunacy of the moment.

“I remember wanting to do it again and again,” Keoghan says. “At the start, I was like, ‘Let’s just get this out of the way.’ But then I was just like, ‘Let’s do it again.’ It became less about being naked and (eventually), I actually forgot that I was.”

Jacob Elordi, Barry Keoghan say the movie's grave scene is more 'sexy' than 'weird'

"Saltburn" is filled with gasp-worthy moments, such as Oliver slurping Felix's bathwater or feeding Felix's sister (Alison Oliver) her own menstrual blood. But the most unsettling scene is at Felix's funeral, after Oliver kills him with poisoned champagne. When the rest of the mourners leave, Oliver lays on top of Felix's grave and sobs. Eventually, he pulls down his pants and begins to thrust his late friend's tomb.

The scene illustrates Oliver's deep infatuation with Felix. In a voiceover, Oliver questions whether he really loved Felix or just wanted to be him. Although moviegoers might be uncomfortable watching his graveside coitus, Fennell is quick to note that it's rooted in a certain Emily Brontë novel.

"This exact thing happens in ‘Wuthering Heights,' " Fennell says. "Heathcliff tries to climb down into Cathy’s grave and the subtext is very much that is what he’s intending to do. So this is very much part of the Gothic tradition.”

“It’s immense grief as well,” Elordi adds. “It’s funny, because it can get taken into this place where it’s weird and surreal and absurd. But it’s almost this desperation to stop death – in a sexy way!”

For Keoghan, Oliver mounting the grave is just "a level up in his obsession" with Felix.

“Where do you even go from there?” Keoghan says. “He’s lost, he’s confused and he doesn’t know what to do. He thinks that’s the right thing to do, but even that doesn’t fulfill. And we’ve all been there!”

“Oh, yeah. Getting out the dirt was tough!” Fennell jokes. "The pictures of you after that (scene) were sublime.”

'The Holdovers':Paul Giamatti movie shows the 'dark side' of Christmas