Imagine there's something growing inside of you. It feeds off of you, snatching sustenance from your rushed granola bar breakfast, and your carb-driven lunch. It wriggles within, sparking ripples across your flesh to remind you its there. It's a part of you, and it isn't. It's not exactly a parasite, but it's not just a baby either. It's an adorable beast that's preparing to rip its way out of you and upend your life as you know it.

From this perspective, it's little wonder that pregnancy has popped up in various frightening forms in heralded films like "Rosemary's Baby," "We Need to Talk About Kevin," and "Alien." Now, into this esteemed company strides Alice Lowe's "Prevenge," a pitch-black comedy about the horrors of surrendering your body and life over to a little stranger who spends nine months treating at your innards as a punching bag and playground.

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Horror fans might remember Lowe as the co-star and co-writer of Ben Wheatley's "Sightseers," which followed a caravanning couple on a murder spree with some tourist traps along the way.  With "Prevenge," the English provocateur steps fully into the spotlight as writer, director and leading lady, playing a very pregnant woman on a ruthless quest of revenge.

Lonely and lying on her back in a cheap hotel with walls so thin she can feel the reverberated thrusts of the amorous neighbors next door, Ruth (Lowe) speaks to the unborn daughter in her belly. But there's no baby talk nor lullabies here; in fact, she gets cross when her pushy child demands she get off her lazy arse and get back to their kill list. "Children these days are so spoiled," Ruth whinges, adding in a mocking tone, "Mommy, I want a Playstation. Mommy, I want you to kill that man!" It's absurd line made wickedly funny with Lowe's slumped shoulders and totally over-it delivery, which shows this isn't out of the ordinary for mom-to-be and yet-to-be-born child. It's their repulsive routine, dedicatedly detailed in a baby book full of childish but ghoulish sketches of death. Now mind you Ruth doesn't want to kill. But as a meddling midwife doggedly reminds her, her life is in service to what baby wants now. And baby wants bloodshed.

Together, menacing mum and her furious fetus cut a bloody path through Cardiff, leaving a trail of bodies along with clues to the mysterious motive of their seemingly random kills. What do a skeevy pet store owner, a charmless DJ, and a blunt business woman have in common besides being the focus of baby's blood lust? That's a question Lowe answers in slow, satisfying reveals, tugged away like long, ghastly strips of peeling sunburnt skin. All the while, Ruth's pronounced belly, cutting a shocking profile for a killer, plays as the film's ticking clock, a countdown to her baby's arrival and a revelatory finale streaked with fragile truth and human horror.

"People think babies are sweet," the unborn daughter muses in a high, sneering baby voice, "But I'm bitter." These are words only Ruth and the audience can hear, and so this single mum is heart-wrenchingly alone in her descent, feeling trapped by her child and its homicidal demands, yet deeply bonded to her. Yet as she adjusts to this perturbing pregnancy, Ruth begins to enjoy giving into baby's cravings for carnage.

"Prevenge's" scenes of slaughter are vicious, not only in their unapologetic gushes of blood, but also in how the camera lingers on the victims' bleeding out, just as Ruth lingers to watch it. Her head crooked, patient, and stoic, these moments after add an unnerving beat to the violence that speaks to Lowe's bold voice. You might think "pregnant lady goes on a killing spree" sounds like the stuff of camp horror. But in quiet, awful moments where the only sound is death rattles and Ruth's impatient sighs, "Prevenge" rejects sinister silliness in favor of a more ferocious and fucked up brand of fun.

Lowe, who was herself pregnant during the film's production, teases out "Prevenge"s sick mystery with grisly kills and gallows humor that makes it illicitly exhilarating. Rejecting the joyous miracle narrative of pregnancy and leaning hard into a new mother's anxiety over losing control, this searingly subversive filmmaker gives voice to maternal fears long considered taboo. It's beyond thrilling to see these terrors tackled with a sharp blade of humor, and a keenly female perspective that recognizes pregnancy as something both astonishing and terrifying. With "Prevenge," Lowe has made a spectacular directorial debut in a film that is defiant, disturbing, and darkly hilarious.

"Prevenge" opens theatrically in New York and Los Angeles, and will be available nationwide on Shudder, on March 24.