"Tell her on how you feel," Sia sings over floating strings on "Salted Wound," a moody, ethereal ballad. "Give her every say she needs to hear/Give your heart, and say come take it/And she will see you're a good man."
The soundtrack to the blockbuster adaptation also features a stripped-down version of Beyonce’s hit single "Crazy in Love" and previously-released songs from Ellie Goulding and The Weeknd.
In contrast to the film's controversial subject matter, the lyrics of Sia's song are almost comforting, perhaps embracing the softer side of the kinky BDSM relationship between millionaire businessman Christian Grey and college student Anastasia Steele?
"Yeah you’ll pull through it," the chorus repeats. "You’re safe."
The "Chandelier" singer has been having quite the year so far, with an appearance as Saturday Night Live's musical guest and a Golden Globe nomination for her song "Opportunity" from the movie musical Annie.
Check out more highlights from the Fifty Shades soundtrack in the video below.