An R-rated suspense thriller, Is God Is, also follows in the tradition of female buddy movies like Thelma & Louise. Kara Young and Mallori Johnson star as Racine and Anaia, young adult twins who still bear the physical and emotional scars of a house fire that nearly consumed them as girls. The blaze sent them into the foster care system and condemned them to a lifetime of stares, derision and pity – leaving them isolated, self-reliant and deeply embittered.

Their isolation is broken when a letter arrives from their mother, Ruby (Vivica A Fox), whom they had presumed dead in the fire but who is now nearing death from the far graver injuries she suffered in the inferno. Reunited at her bedside, Ruby reveals that the fire was an act of domestic violence committed by their father (Sterling K Brown) and asks her daughters to avenge her. “Make your daddy dead,” Ruby instructs them. “Real dead.” Anaia, the shy, “ugly” younger twin, recoils from the request; Racine, the fearless and more conventionally “beautiful” sister, embraces it eagerly, setting them on a Kill Bill-style quest for closure.

For those who have had their fill of sins-of-the-father allegories, relax: Is God Is deftly draws from the Black church’s warnings about generational curses without tipping into outright sermonizing. Aleshea Harris, making her feature writing and directing debut after staging Is God Is off-Broadway, forces her protagonists to confront a grim paradox: whether a cycle of inherited violence can only be broken through an act of violence itself. “We come from a man who tried to kill our mama and a mama who wants us to kill that man,” Racine says, hoping to sell Anaia on the mission. “It’s in the blood.”

But where Beatrix Kiddo was an immensely capable weapon, Racine and Anaia are neither trained mercenaries nor especially strong of stomach. They pass the time on their road trip debating the most efficient way to carry out what still amounts to an inconceivable task – Anaia suggesting poison, Racine a stoning.

If the twins possess any superpower, it’s telepathy. Harris punctuates their silent exchanges with ornate antebellum-style typefaces, heightening an intuitive chemistry familiar to anyone who watched Yvette Nicole Brown decode Keke Palmer’s impossibly nuanced facial cues on Password, or lives this unspoken truth.

For a first-time feature director, Harris demonstrates a remarkably firm grasp of scale, pushing in on the claustrophobic intimacy of the twins – matching clothes, brushing their teeth shoulder to shoulder, speaking in stereo – before pulling back to luxuriate in the vast, multihued landscapes they traverse on their blood-soaked quest through Louisiana farmland. Really, the whole adventure could easily be set to a spaghetti western score. (Instead, there’s trap music). For all the fatalism hanging over their journey, Harris finds real exhilaration in simply watching Racine and Anaia move through the world together. On the open road, their scars and inherited rage briefly loosen their grip, giving way to moments of girlish play, boredom and freedom. The metaphor, for Black life and labor, is unmissable.

Harris affords the same richness to the eccentrics and stragglers the twins meet along the way. Erika Alexander, in the midst of a post-Living Single renaissance, is an absolute riot as Divine – the preacher paramour their father took up with after torching their mother, and who remains hopelessly devoted to him still. Mykelti Williamson feels almost unfairly well cast as Chuck Hall, a garrulous personal injury lawyer rendered mute, because the role affords him only a handful of scenes and lines; yet his physical performance ultimately rivals the twins’ own wordless chemistry. Janelle Monáe is a flustered, diabolical mess as Angie – the twins’ father’s wife, in a mad scramble to escape a life of comfort the twins could only dream of for themselves.

Most impressive, though, is Harris’s resistance to the gravitational pull of Brown’s megawatt charisma, blunting it as casually as his character does a cigarette. Rather than grant him an early close-up and risk disarming the audience, she reveals him in fragments – his rictus smile, his turned back, the tendrils of cigarette smoke curling into the night as his family screams inside the burning house – before finally showing him in full, reshaping TV’s most congenial leading man into an exquisite, genuinely unlikeable final boss. She should take a bow: It’s a feat none of her Hollywood peers can claim, and not for lack of trying.

Is God Is may borrow from an old narrative formula, but it reframes it into something sharper and more searching. It shows that stories rooted in Black trauma don’t have to be pulled down by it. Vibrancy and texture are what give a killing spree its stakes, after all, and this one ends with an understated affirmation of the human spirit. How’s that for a twist.

• Is God is is out in US cinemas on 15 April and in the UK and Australia on a date to be announced