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,...