My Friend Dahmer is an adaptation of a graphic novel by John Backderf. Backderf’s comic told the story of his high school friendship with Jeffrey Dahmer – who shortly thereafter became one of America’s most notorious serial killers. While I haven’t read the comic, the appeal is obvious: what would it be like to go to school with a serial killer? Would you pick up on his underlying deviance, or would he just have seemed like another high school weirdo?

Marc Meyer’s film isn’t especially interested in that question, largely shifting perspective from “Derf” – played by Alex Wolff – to Dahmer himself (Ross Lynch, recently seen as Harvey in The Chilling Adventures of Sabrina, here impressively detached and increasingly deranged). Meyers adeptly sidesteps the obvious dangers of either explaining or empathising with Dahmer … which, unfortunately, leaves the film without much of a purpose.

My Friend Dahmer is appealing despite this failing. When Dahmer initially befriends Derf’s group, its prank-heavy sequences play as effective (if undeniably dark) high school comedy, while later scenes are soaked in deepening dread. Lynch and Wolff deliver memorable performances, but they have the misfortune of appearing in a film whose lack of purpose leaves it entirely unmemorable.