Transitioning from Disney Channel heartthrob to darker, more mature roles is no easy task, but Ross Lynch makes it look effortless. For years, fans have known Lynch as Austin Moon on Austin & Ally and Brady in Teen Beach Movie, but he'll soon be known as one of history's most vile characters: Jeffrey Dahmer.

The 21-year-old actor stars in My Friend Dahmer, in which he portrays the notorious serial killer and necrophiliac who ate and dismembered his male victims. The true story, based on Derf Backderf’s graphic novel, is set before Dahmer's most horrific crimes were committed, offering the audience a glimpse into his life as a "regular" teenager.

"I think it’s kind of a sad story," Lynch told MTV News by phone last week as the film had its Tribeca Film Festival debut. Caught in the middle of his parents' bitter divorce and ignored by many of his classmates, young Dahmer would retreat to a secluded hut to perform experiments on dead animals.

Later in high school, Dahmer found friends — or at least, the closest thing to friends he'd ever have. Derf (Alex Wolff), Mike (Harrison Holzer), and Neil (Tommy Nelson) made up the “Dahmer Fan Club,” sneaking Dahmer into every yearbook club picture and egging him on to perform his (offensive) cerebral palsy imitation.

It's easy to see that Lynch is a dead ringer for Dahmer, but the realization didn't freak him out as much as it did the rest of the cast and crew. Lynch said that people who actually grew up with Dahmer would ask him to remove his character's glasses while they were talking to him, because he “just resemble[d] him a little too much.”

Thankfully, the vibe on set wasn't too serious, despite the film's subject matter. Lynch explained that the four main stars often lightened the mood with a little help from Nicolas Cage. In their downtime, they liked to huddle together and watch a montage video of Cage's biggest freak-out movie moments. “It would be quiet on set and all of a sudden you'd hear us screaming in a corner, screaming Nicolas Cage lines,” Lynch laughed.

But exactly what about playing a brutal serial killer would appeal to a wholesome Disney actor? For Lynch, My Friend Dahmer is reflective of the new direction he wants for his career. “I was looking for a challenge,” he admitted. “I was looking for something I could really sink my teeth into.”

While the project is a risk for Lynch, whose young fans love him on Disney and in his pop band, R5, darker, juicier roles are enticing for any actor. This is the path Lynch wants to take, and so far, he's killing it.

[My Friend Dahmer screened at Tribeca Film Festival and is expected to premiere in theaters this fall.]