An ungainly yet strangely captivating oddity, “London Road” snags your attention from the get-go in the manner of any razor-edge experiment: By making you wonder, what on earth? As soon as that question is answered, however, you’re hooked, and this unconventional examination of the ripple effect of real-life killings on a quiet English town has worked its curious magic.

Essential to the spell is the movie’s most theatrical conceit: A script, by Alecky Blythe, gleaned entirely from interviews she conducted with the town’s residents after the murders of five prostitutes in 2006. Using a technique called verbatim theater (similar to that used by Clio Barnard in her 2011 film, “The Arbor”), Ms. Blythe reproduces exact phrases, cadences and speech patterns, including every hem and haw.

“Everyone is very, very nervous, um, and very unsure of everything,” says Julie (Olivia Colman, perfection), a single mother with little sympathy for the victims. The refrain is picked up by other residents, the spoken words sliding imperceptibly into song as Adam Cork’s score becomes a libretto of sidewalk anxiety. Slyly turning natural verbal rhythms into eccentric choral numbers, Mr. Cork creates a serial-killer opera whose genius is to transform the banal into something exceptional.

Original, audacious, funny and perceptive — a sequence involving the murdered women is unexpectedly haunting — “London Road” (adapted by the director, Rufus Norris, from his successful London stage musical) will either fascinate or alienate. Yet the artifice of the form works something wondrous with the material, highlighting the generic nature of our response to extreme violence. These events unfolded in Ipswich, but they could have occurred anywhere.