Fifty Shades of Grey: The Story Behind Beyoncé’s “Crazy In Love” Update

If you were surprised to hear Beyoncé lend her trademark uh-oh-uh-ohs to the Fifty Shades of Grey film, you weren’t the only one.

“With everything she’s been doing recently, the surprise factor has been a big part of it,” says violinist and recording artist Margot, who arranged and played the strings on the new version of “Crazy in Love” that’s featured in the just-released trailer. In fact, Margot didn’t even know if her own contributions had made the cut until she watched the trailer for the first time on Thursday.

“It was one of those things that happened on the spot, and you have to jump when you know it’s a good opportunity,” she tells TIME.

The track was produced by Boots, who helmed much of Beyoncé’s last album; he and Margot have worked together on a number of projects, including Beyoncé and Boots’ recent mixtape. A few weeks ago, Boots called Margot to say he was working on a movie trailer and needed some string contributions — but he needed them that night. Margot met up with Boots in Brooklyn, he played her the track (which he had recorded just that day, not long after Bey’s team reached out) and she immediately began laying down the violin parts you hear before Beyoncé ever recorded vocals.

“It inspires me to work on other artists’ songs [because] it pushes my boundaries in a direction that I wouldn’t necessarily come up with,” Margot says. “Obviously I know how ‘Crazy in Love’ goes, but I knew there was the possibility her vocals would be different. It’s almost more vulnerable and beautiful this way, because you do do crazy things when you fall in love. To hear the mood reversed and flipped makes it even more powerful.”

Despite their success in remaking the track for the highly anticipated film adaptation, neither Margot nor Boots have actually read the book.

“It’s funny, when it comes to scoring films and making music, it’s more about the mood that you’re capturing anyway,” she says. “We didn’t necessarily need to know the storyline to make something dramatic and sensual.”