Watch your back "Heathers," because "Tragedy Girls" is coming to snatch your crown. The teen horror-comedy about aspiring serial killers hits SXSW with a heady mix of menace and moxie that insures it'll be a crowd favorite an instant cult classic. A tantalizingly dark humor dances through "Tragedy Girls," a story that's as much about friendship as it is about the twisted ambition.

Superhero movie scene-stealers Alexandra Shipp ("X-Men: Apocalypse's" Storm) and Brianna Hildebrand ("Deadpool's" Negasonic Teenage Warhead) star as a pair of churlish cheerleaders whose thirst for internet stardom is matched only by their IRL bloodlust. When their sleepy Midwestern town becomes the hunting grounds for a serial killer (Kevin Durand in grumbly slasher mode), McKayla (Shipp) and Sadie (Hildebrand) take the opportunity to capture him. But not so they can bring him to justice. Instead, these enterprising teen terrors want a fall guy for a killing spree of their own.

Pitching dismembered heads and splashes of ropey blood along with biting one-liners, "Tragedy Girls" is a comedy unrepentantly gaga over gore and horror. These self-proclaimed "tragedy girls" (their Twitter handle) whoop and rally over their murder scenes with the kid of ghoulish glee that horror fans share over bonkers onscreen kills. This reflective edge is part of what makes this killer comedy so cutting. On one level, it's a blast to chase Sadie and McKayla as they ditch out on their loving parents to slaughter a self-righteous classmate who dared oppose their prom plans, a deliciously deranged vicarious thrill. But on the other, the script by Chris Lee Hill and Tyler MacIntyre slyly unfolds darker details of their backstory that make it harder and harder to reconcile our affection for these homicidal antiheroines.

Bolstering "Tragedy Girls" sick and slick appeal is the kinetic chemistry of Shipp and Hildebrand, who satirize female friendship by pushing its most savage bits into a life or death showdown. But in moments of peace, they're believably best friends, who share shorthand, secrets, and a killer fashion sense of crop tops and willfully clashing patterns that brings "Tragedy Girls" to life in the way Cher and Dionne's to-die-for plaids did in "Clueless." (Teens today may not dress this effortlessly cool yet, but they'll aspire to now.) All this bad-girl bonding is touching and enviable, even when its in pursuit of something truly atrocious, a prom night to remember.

A strong supporting cast infuses this ferociously funny flick with verve. "Hunger Games" Josh Hutcherson doing a pointedly douche James Dean impression smolders from a motorcycle and speaks in a faux-casual whisper that makes him the perfect object of affection (then annihilation). Playing Sadie's secret crush, Jack Quaid, with big eyes and an earnest sincerity grounds the real-world consequences of these gruesome girls' hunger for destruction. And though Craig Robinson feels a bit miscast as a local firefighter, who is intensely lusted after for his muscles and supposed sex appeal, he musters enough charisma and physical might to pull off one of the film's wildest action scenes. But make no mistake: this is Shipp's moment.

As the cool-headed Sadie, Hildebrand holds it down with smirks, side-eye, and quips like, "To make an omelet you have kill some ex-boyfriends." But it's Shipp's hot-headed and loud-mouthed McKayla who cranks up the comedy in "Tragedy Girls," dropping snarky one-liners like grenades, causing explosions of laughter. This dazzling ingenue with a dark wit brings a bubbliness so effervescent to scenes of slaughter that it's a disturbing and dizzying delight. Hell, she practically skips through murder scenes, and then offers that same unwinking enthusiasm to interactions with her affluent, supportive, and clueless parents. It makes for a killer unlike this genre has ever seen before. Her chipperness and charm is not a cover. It's who she is, in school, at home, on the killing fields.

This conflict of cute and creepy makes "Tragedy Girls" a rich and wild must-see, full of eye-popping gore, gleeful gallows humor, and addictive attitude. Behold: the new class of bad girls have arrived, and they're badass.

"Tragedy Girls"made its world premiere at SXSW.