There has already been one intriguing film about notorious serial killer Jeffrey Dahmer—David Jacobson’s 2002 “Dahmer,” in which Jeremy Renner made his breakthrough in the title role. Now we have another, “My Friend Dahmer,” adapted by Marc Meyers from a fact-based graphic novel by John “Derf” Backderf, in which Ross Lynch, a former star on the Disney Channel, proves that he’s not just another pretty face. At once sympathetic in its portrayal of a boy tortured by circumstance and eerie in its presentiments about what he would become, it’s emotionally unsettling but strangely moving.

The picture is extremely limited in its scope, covering Dahmer’s senior year at his Bath, Ohio high school. He’s a perpetual outcast there, and finds little comfort at home: his mother Joyce (played with terrifying intensity by Anne Heche) is mentally disturbed, having only returned from an institution, and his frazzled father Lionel (Dallas Roberts), a chemist who admits that he spends too much time in the lab, has trouble dealing with her, Jeffrey and younger son Dave (Liam Koeth).

The sole pleasures Dahmer seems to have are centered in his backyard shed, where he puts roadkill he scoops up from the pavement into jars with chemicals provided by his dad: he likes to watch the flesh decompose, leaving the skeletons behind. He also shows signs of wanting to kill, at one point trying to shoot a dog he’s led out into the woods. And he becomes fixated on Dr. Matthews (Vincent Karthauser), the local physician who regularly jogs past his house. At one point he’ll even lie in wait for the man with a baseball bat at the ready—after making an appointment for a physical.

These preoccupations, however, take second place to the camaraderie he develops with a trio of nerdy classmates—aspiring artist Derf (Alex Wolff), Neil (Tommy Nelson) and Mike (Harrison Holzer)—who watch in amazement as he abruptly pulls a spastic riff in the hallway one day and decide to make him their mascot. They’ll use him to disrupt the place with pranks like inserting him into every club photo for the yearbook. But this is hardly a real friendship: it’s an arrangement of convenience, and when Dahmer proves to them that he can get a date for the prom, things do not turn out well. A similar outcome follows his attempt to befriend a hopped-up drug-dealer named Finn (Miles Robbins).

The movie ends with Dahmer’s graduation, which only Lionel—now living out of a motel room—attends, Joyce and Dave having suddenly gone off to her parents. Desperately lonely, and increasingly prone to thoughts of homicide, he has an encounter with the apologetic Derf—an episode that may be the script’s sole misstep, a rather crass attempt to generate tension—before picking up a hitchhiker.

“My Friend Dahmer” studiously avoids overt violence, but the suggestion that it’s imminent is always present. That comes across in Lynch’s performance, which goes beyond a portrait of a bullied, awkward teen to look ahead to what Dahmer will become. Lynch handles that with considerable subtlety, adopting a stooped-over posture and glassy-eyed, vacuous stare that indicate undercurrents of hostility that can erupt in outbursts when his lust goes unfulfilled. In his hands what might have been a stunt becomes something more.

Supporting him ably are Heche and Roberts, who draw a portrait of an unhappy, contentious marriage that feels authentic, and Wolff, Nelson and Holzer, who are spot on as would-be rebels who use Dahmer for their own ends. Production designer Jennifer Klide and costumer Carla Shivener capture the period detail of semi-depressed suburban Ohio in the early nineties without overdoing it, while cinematographer Daniel Katz and editor Jamie Kirkpatrick maintain the moody tone Meyers was after but keep the sense of menace submerged. Andrew Hollander’s score is similarly undemonstrative, and the use of pop songs is imaginative, with the prom scene—which could give “Carrie” a run for the money—appropriately garish, both visually and aurally.

Some will question why “My Friend Dahmer” should exist at all. But it doesn’t glorify or explain away the horror its subject perpetrated. Rather it seeks to understand, empathetically but without tears, how such a person was shaped. It can offer only partial answers, of course; people like Dahmer will always remain an enigma to us in the end. But Backderf and Meyers’ invitation to ponder the making of a killer too easily dismissed as an inexplicable monster is at once disturbing and curiously moving.