Though best known for her masterful, unpredictable albums as a bandleader and singer-songwriter, PJ Harvey has also established an erudite parallel career composing scores for film, television, and theatre. Her score for the new West End theatrical production All About Eve, an update of the Oscar-bedecked 1950 film, is the latest in a string of collaborations with director Ian Rickson. Harvey wrote a couple of songs with proper vocals: “Sandman,” for Gillian Anderson, in the role that got Bette Davis nominated for Best Actress; “The Moth,” for Lily James, who plays the show’s namesake pseudo-ingénue.

But of the tracks released so far from All About Eve (Original Music), Harvey’s authorial voice can be most resoundingly felt in the unsettling instrumental titled “Descending.” An off-kilter clockwork of oscillating synths, breathy woodwinds, and undulating strings gives queasy new meaning to Davis’ classic line from the film: “Fasten your seat belts, it’s going to be a bumpy night.” Then a jazzy drum freakout arrives as a reminder that there are no seat belts.

Correction: An earlier version of this review incorrectly stated that Bette Davis won an Academy Award for her portrayal of Margo Channing in All About Eve. Davis was nominated for Best Actress at the 23rd Academy Awards, but she lost the honor to Judy Holliday, who played Emma “Billie” Dawn in Born Yesterday.