Perpetrator defies convention. Even if you tried to squeeze Jennifer Reeder's latest horror outing into a tidy box, it would simply ooze its way out, not unlike the blood that seeps through its (nearly) every scene.

Said blood comes in many forms: nosebleeds, periods, gaping wounds. It stains teeth, leaks through bandages, and coagulates in thick, glopping puddles. Yet despite these unsettlingly tactile visuals, Perpetrator does not treat blood as a source of horror. Instead, blood is power, blood is untapped potential, blood is even a source of salvation. We quickly come to realize that the true horror of Perpetrator lies in the threats young women face to their bodily autonomy, a theme the filmhas in common with another 2023 Shudder release, Laura Moss' Birth/Rebirth.

To hammer this point home, the director opens Perpetrator with a scene of an unknown assailant kidnapping a teenage girl named Evelyn. The masked attacker brings her to his lair, sedates and binds her, and tells her things are about to get a lot worse. "Girls like you don't know what they've got until it's gone," he snarls before the credits — a grainy montage of surgical instruments and blood — kick in.

The darkness of this sequence may make you think that Perpetrator is about to veer into torture porn territory, or into a straightforward thriller where people attempt to hunt the suspect. But that couldn't be further from what Reeder delivers. Perpetrator free-wheels through genres and influences, dancing from coming-of-age to noir to different flavors of horror without missing a beat. The seeming lack of cohesion lends Perpetrator a surreal quality — similar to what we saw in Reeder's 2019 directorial feature film debut Knives and Skin— making for a singular viewing experience with feminist horror sensibilities that will linger under your skin.

What is Perpetrator about?

While Perpetrator begins with Evelyn's kidnapping, Reeder quickly switches focus from her fate to the film's protagonist Jonny (Kiah McKirnan), whom we encounter as she commits a burglary to help her father make ends meet. However, that's not the end of her troubles. Jonny's never met her mother, she's prone to strange nosebleeds, and she's on the verge of her eighteenth birthday. That last one may not mean anything to her yet but it does to her father, who reveals in a troubled phone call that something major will happen to her when she turns 18 — and he isn't equipped to deal with it. (That problem might have something to do with the fact that whenever he looks in a mirror, his face ripples and changes into someone else's.)

As her birthday approaches, Jonny goes to live with someone who isequipped to deal with this mysterious change: her Aunt Hildie (Alicia Silverstone). Emerging from her large house in ensembles of black cloaks and furs, Silverstone exudes a delightful stone-cold witchiness that immediately clashes with Jonny's rebellious teen energy. Intimidating, severe, and just the right amount of funny, Hildie feels like a cross between Morticia Addams and The Chilling Adventures of Sabrina's Aunt Zelda. When Silverstone appears, Perpetrator truly crosses into bizarro territory.

For all her quirks, Hildie is far from the only eccentricity in Jonny's life. Beyond the known physical changes that come with adolescence, she's dealing with some wild bodily anomalies, like her aforementioned nosebleeds and their connection with other people, and the fact that, according to her school nurse, she could possibly have multiple hearts. Hildie walks Jonny through these changes, revealing that every woman in their family develops a special hyper-empathy on their eighteenth birthday. She calls it the Forevering, describing it as "possession in reverse."

Perpetrator never lays out the full specifics of the Forevering for us, but it doesn't need to. Mimicry of body language, shifting faces, and spooky in-unison dialogue get the point across easily (and creepily). What's more important is that the Forevering marks Jonny's official transition to adulthood. Think of it as a kind of second, supernatural puberty where Jonny will once again learn more about her changing body.

Perpetrator's horror is all about bodily autonomy.

As Jonny learns more about the Forevering, Reeder pairs her supernatural coming-of-age story with some slasher movie beats. Girls at Jonny's new school have been disappearing for a while now, stalked and abducted by the masked man from the opening sequence. For most of the film, Reeder leaves the attacker's violence toward his victims a mystery, allowing our imaginations to run ragged with fear.

This omnipresent threat also hangs over the town and school, to the point that concerned Principal Burke (Chris Lowell) hosts mandatory self-defense classes for his female students. Unfortunately, he gives them the worst advice of all time, stoking paranoia and setting up a culture of victim blaming. "Danger lurks around every corner!" he proclaims. "Your survival depends on you and only you."

While Principal Burke and his school don't offer the same bloody frights as Aunt Hildie and the Forevering, Reeder steeps the school environment in its own kind of surrealism. An especially deranged and graphic school shooting drill results in some of the film's most unsettlingly funny dialogue. "My parents are going to slaughter me for being killed," complains a new classmate of Jonny's. It's one of many lines that would be right at home in Heathers— a classic teen dark comedy that feels like a solid comparison point thanks to Jonny's status as an outcast and her connection to a trio of popular girls. (Reeder draws from an eclectic group of film references, including Silence of the Lambs and Spartacus.)

• Alicia Silverstone goes horror in eerie 'Perpetrator' trailer
• What is Shudder? Everything you need to know about the horror streaming platform.
• The best women-centric and feminist horror movies
• 10 hidden gems of horror found on Shudder
• Early 2024 TV deals include several premium Samsung QLEDs and cheap TCL and Hisense QLEDs

The deliberate weirdness of Jonny's high school speaks to how strange it is to grow up in a time characterized by fear of losing control of your body and facing down attacks. But as Jonny teams up with fellow outcast Elektra (Ireon Roach) to track down the town kidnapper, these topical trepidations become a source of communal connection. Jonny's own powers of empathy deepen that connection even further, resulting in some legitimately cathartic moments.

The catharsis of Perpetrator comes not just from its plot and timely themes, but from how it wields its cinematic form. Thanks to Reeder's direction with editing by Justin Krohn, cinematography by Sevdije Kastrati, and a score by Yeah Yeah Yeahs' Nick Zinner, the film's mishmash of tone, genre, and influences is confounding yet refreshing, as wild as its young protagonists when given a chance to just be themselves. Also refreshing is seeing Silverstone in such an out-there role; not only is her performance a ton of fun, but the casting feels like a passing of the teen movie torch from classics like Clueless to something more contemporary and demented.

With all these conflicting ingredients, it's a wonder Perpetrator comes together at all, let alone in such a frightful, freeing fashion. It's reminiscent of the bloody cake Hildie serves Jonny on her 18th birthday: tempting, uncanny, and something you simply must sink your teeth into.

Perpetrator debuts in select theaters and on Shudder Sept. 1.

UPDATE: Aug. 30, 2023, 3:24 p.m. EDT Perpetrator was reviewed out of its North American premiere at the Tribeca Film Festival. The review has been republished to celebrate its debut in theaters and on Shudder.