Birth/Rebirth will grab you by the guts with its mercilessly scary opening sequence. It's not just that Laura Moss's directorial feature debut delves into a terrifying Frankenstein-inspired tale. It's not just that her Sundance stunner boasts body horror with a matter-of-factness that is starkly unnerving. It's how the opening deftly illustrates an all-too-common fear that has arisen in this age of an overturned Roe v. Wade.

Birth/Rebirth begins over black, with just the blip of an ambulance's siren. The dulled chatter of paramedics chimes in, then the choked sound of a gasp. A woman wakes with an oxygen mask forced over her face. Moss mercilessly places us in the terrified patient's POV as she looks on helplessly while surgeons with bloody hands carve away at her belly.

"Your baby's gonna be fine. I promise," a well-meaning surgeon insists. In a weak voice, this unseen woman asks, "What about me?" But she is forgotten as the hospital staff rushes to rescue the fetus from her womb. The POV camera's focus blurs as hers does. Then the camera shakes violently, reflecting how her body seizes, loses grip, and dies. Finally, the camera makes a cold cut to her naked corpse, still sliced open from the surgery and laid dispassionately on a morgue's slab, ready for her organs to be harvested for donation.

Here, gruesomely and efficiently laid out is the fear of those who have uteruses, that we are not seen as people by the Supreme Court but as a vessel for a little stranger. To be a mother is to sacrifice your body, your free time, your ambition, and maybe even your right to live. But this is just the start of the maternal terror that Moss spawns in Birth/Rebirth.

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What's Birth/Rebirth about?

Judy Reyes and Marin Ireland face off in "Birth/Rebirth" Credit: Shudder

Forget the dead mother on the slab. Birth/Rebirth's focus swiftly shifts to the mothers who will contend with her corpse and her surviving child. Celie (Judy Reyes), a nurse in the obstetrician unit of her hospital, is warm with patients, friends, and her playful daughter Lila (A.J. Lister). Her introduction shows her gently stroking the newborn's foot as it lies in an incubator, unaware of the loss of a mother it'll never know. Then, there's Rose (The Boogeyman's Marin Ireland), the morgue technician who photographs the remains and plunges her hands into the open cavity of its guts with a blank expression.

At the start of this story, they are strangers. Slowly but surely, they become an eerie Odd Couple, polar opposites who forge a mercurial friendship in a shared apartment. But the reason why is pure Frankenstein, binding the women through sci-fi horror motherhood.

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You see, when little Lila dies abruptly, the calculating and cold Rose steals her remains, then resurrects her with an experimental treatment. Discovering this disturbing miracle, Celie rededicates herself to her child, and by extension to Rose and the experiment's success. But there's a terrible cost that keeps this kid any kind of alive.

Birth/Rebirth is not for the faint of heart.

Marin Ireland gives us cold, and it's everything in "Birth/Rebirth" Credit: Shudder

But that's appropriate, because — as I understand it — neither is motherhood. And this movie is deeply vested in the fears of what it means to be a mother. Celie and Rose must face all kinds of horrifying challenges in keeping the revived Lila alive. They must be patient as she hits strange milestones or acts out only a way only a once-dead kid might.

Body horror comes into play as Rose's science experiment gets grisly. And Moss's approach does not flinch at wounds, staples, blood, and the kind of pulpy mess that menstruators know all too well. But then there are also simple, haunting shots, like a mother carrying her dead child's clothes in a ziplock bag onto a hospital elevator, returning to a home that's quiet and empty. In such stillness, we are welcomed into Celie's pain like a warm bath, not realizing what lurks within these waters.

A sneaky soundtrack scrapes at our nerves, as groans, low shrieks, and soft clangs — reminiscent of distant metal — create an atmosphere that is chilling in its sense of sterility. For all of Celie's passionate glares and powerful declarations of love and duty, Rose is eerily, ruthlessly logical and cold. She delivers a handjob in a bathroom with the same dead look in her eyes as when she photographs a cadaver at work. But beneath this icy exterior, her heart begins to burn as she and Celie grow closer.

Amid the body horror, maternal terror, and wicked trespasses these mothers tromp into, Birth/Rebirth stuns with its macabre sense of humor. It's not laugh-out-loud funny. It's the kind of funny you find a funeral. It's the chaotic collision that happens when frankness overrides the facade of civility. So, a line as simple as "I have a futon" made me chuckle darkly. In context, it's hilarious because of the flatness of Rose's delivery, the reaction in Celie's tear-swelled eyes, and the logic that splats in between them like a blood clot. It's the kind of dark humor that will make some cringe and others feel like they've just gotten an injection of adrenaline.

Birth/Rebirth is a scorching directorial debut.

Credit: Shudder

It's unnerving that this is Moss's directorial feature debut, because it's so damn good. The production designer-turned-director has made a film that's ruthlessly intimate, meticulously detailed, and shiver-inducingly scary. She's taken a chunk of Mary Shelley and brought it to fresh life with a lightning jolt from the war for bodily autonomy. But within a clever concept — with added oomph by a shocking reveal — Moss has also built a story of a fascinating female friendship.

Her incredible cast lures us in with their high-contrast heroines, with Reyes and Ireland giving performances that are grounded yet electrifying. That these women feel so real is part of what makes the rest of the movie give us goosebumps. Within all that is a wicked ribbon of humor that understands that in grief, pain, panic, and love, there is something wild that cannot be tamed. And then, where so many clever-premised horror fails to stick the landing, Moss's movie ends exactly where it ought to, leaving us gasping — though perhaps hungry for more.

Simply put, Birth/Rebirth is a uniquely thrilling vision of horror, and Moss is a director to watch. Keep an eye out for both.

Birth/Rebirth opens exclusively in theaters Aug. 18.

UPDATE: Aug. 11, 2023, 4:57 p.m. EDT Birth/Rebirth was originally reviewed out of its World Premiere at the 2023 Sundance Film Festival. The review has been reposted to celebrate the film's theatrical debut.