SPOILER ALERT: This story discusses major plot points, including the ending for “Saltburn.”

Singer-songwriter Sophie Ellis-Bextor was already a fan of Emerald Fennell when she was approached about the use of her 2001 hit “Murder on the Dancefloor” in “Saltburn.” “I loved ‘Promising Young Woman,’” Ellis-Bextor says. But what really sold it to her was the pitch: “A naked man dancing through the rooms of a stately home…I’ve got a quirky sense of humor, and my main thing was, ‘I’ve got to see that.’”

Set in 2006, Oliver is a student at Oxford University who becomes dangerously obsessed with the suave and good-looking aristocratic classmate Felix, played by Jacob Elordi. When Felix invites him to spend the summer at his family’s estate Saltburn, things slowly take a turn as it is revealed that Oliver has been lying the entire time about his background and family. When Felix threatens to expose him, Oliver turns things into a family tragedy for the Cattons, killing them, one by one. The song ends the film that sees Barry Keoghan’s Oliver Quick staking his claim on the Catton Family’s estate after orchestrating a series of events that lead to their deaths, by dancing naked through the house. “I just love that song so much,” Fennell says. “It was the only song that seemed fitting to tie the end of the film together.”

Fennell called on choreographer Polly Bennett to work with Keoghan on his body movement, and cinematographer Linus Sandgren framed the scene in a single shot following Oliver, who is having this post-coital and euphoric moment of joy.

“It’s a dark, twisted and witty ride,” says Ellis-Bextor of the plot. “When you get to that point, the song has something that has the sweetness of the pop, but also a sting in the tail with the lyric.” She adds, “Lucky me, how nice to be surprised by an old friend like that song.”

The song was a huge hit for Ellis-Bextor, peaking at No. 2 on the U.K. music charts and becoming a worldwide top ten hit.

Reflecting on its success, she says the song opened doors for her as a solo artist. Until then, she had found fame as the lead singer of the indie band Theaudience. A collaboration with DJ Spiller on the song “Groovejet” became the biggest hit of the year, but it was “Murder on the Dancefloor” from her debut album that she says “consolidated my opportunity to have a solo career and to make more albums under my name.”

Ellis-Bextor was more than happy to perform it in front of audiences at the “Saltburn” premiere. Does she like the song? “I love singing all of my songs. You do hear stories about artists not liking some of their songs. That must be so sad.”

As it turns out, Fennell isn’t alone in being a fan. “I remember Dave Grohl coming over to me at a party and saying, ‘You have no idea how much we play your song in our house,’” Ellis-Bextor laughs. “Sometimes it’s quite unexpected people that have got a soft spot for ‘Murder on the Dancefloor.’” It’s not just Oliver Quick.