Night rarely falls on the harsh, sun-bleached world of Aleshea Harris’s film “Is God Is,” a revenge parable about the breaking, or the burning, of the Black family. A glare backgrounds the protagonists, twins with matching cornflower box braids, named Racine and Anaia, who carry on their skin, to varying degrees, burn scars. Racine and Anaia are motherless and fatherless. They work as cleaners at an office; at one point, Racine exposes a raised scar, on her arm, to a pretty, professionalized woman, who recoils in disgust, activating Racine’s violent instincts of reprisal. Anaia’s scarring is a different situation. Her face is keloided up to the neck, like raised tree roots, like the meaning of Racine’s name. Racine, played by Kara Young, is a beauty in the face but a bullet in the body, ready to attack any and all who shrink back in disgust at the sight of her sister, who is played by Mallori Johnson. The opening scene is in sepia flashback, and it shows the twins as children, filmed from the back, at a playground. A child taunts Anaia offscreen, prompting Racine to beat him bloody.

One day, Racine receives a letter from a woman claiming to be the twins’ mother, Ruby, asking them to come see her, as she is dying. Anaia, feeling jilted that the letter was addressed only to Racine, cowers in hurt, like a street cat. How was she forgotten? Aren’t Racine and Anaia one? The sisters, brushing their teeth, speak telepathically, inner thoughts printed in caption text across the screen. When they do go to meet their mother, the encounter is a shock to the twins; the scene, in its gothic splendor, is a shock to the viewer. Ruby, played by Vivica A. Fox, is a bedridden queen, mummified in compression wraps, immobile except for the lips, and attended to by nurses wearing gold door-knocker earrings, as if ladies-in-waiting, who file her talon nails and braid the ropes of her wig. A mask obscures her own extraordinary scarring. Racine, manic with zeal, reasons that Ruby must be God, given that she created the twins. In flashback, this god tells us what happened to her. The twins’ father (Sterling K. Brown), credited as Man in the script, slipped into the family home, knocked her unconscious, and set her on fire. (He is shot from the mouth down, in classic horror-camp style.) The flames claimed the girls as collateral, scarring both of them but disfiguring Anaia, who worked the hardest to save Ruby. She informs her daughters that their father took up with other women, and gives them information to set them on their way. Her dying wish: “Make your daddy dead,” Ruby/God commands. “Real dead.”

Reviewers have pressed this film into the Southern-gothic mold, invoking Kasi Lemmons’s “Eve’s Bayou,” and into the Greek-tragedy mold, invoking Sophocles. Of course. But there is a nearer antecedent, which should always be on our minds when we are faced with the diptych of child sisters: “The Color Purple.” (By using the motif of twins, Harris, a playwright who first staged “Is God Is” at the Soho Rep some eight years ago, is concentrating on the spectre of sister love which has long haunted Black literature.) Harris has taken the religious patina of Alice Walker’s tale—most chiefly the Christian God, to whom Celie writes her heartsick journal entries after she is separated from her beloved sister, Nettie, by the monstrous Pa and the vindictive Mister—and dirties it, wisely. Celie forgives her tormentors, in “The Color Purple,” ushering in redemption at the novel’s and film’s ends; Harris deprives her story of that final, harmonic beat. A heretical energy powers the script of “Is God Is” (though Harris’s bending and twisting of language isn’t matched by the movie’s visual sphere, which never quite mirrors the chilling filmic tableau of the dying Ruby and her nurses). And so, naturally, an old-fashioned controversy is brewing around the film. Blasphemy, the detractors—many of whom are Black, and male—are claiming. How dare the film depict God as female, and as murderous? How dare it depict Man as callous and abusive? The righteousness is cover for egoistic anger, and it also echoes the reception to “The Color Purple,” two generations ago, which was criticized for being a so-called dangerous representation of Black men.

Spoilers ahead. God has ordered a crusade. “We ain’t killers,” Anaia insists. Racine, her voice moving like sludge, retorts, “We come from a man who tried to kill our mama and a mama who wants to kill that man. It’s in the blood.” Their weapon of choice, invented out of necessity, is a rock in a sock. On the open desert road, Racine and Anaia track the other women Man has taken up with, following their trail like hounds. They meet a cult leader, Divine (Erika Alexander), and a repressed housewife, Angie (Janelle Monáe), who is Man’s latest wife. The confrontations result in wild, libidinous killing. The odyssey ultimately brings the twins to a bourgeois mansion in the desert, Man’s home for his replacement family, which includes another set of twins: two strapping young men, Scotch (Xavier Mills) and Riley (Justen Ross). Anaia and Racine pose as strippers, ordered for the boy twins, one assumes, by Daddy. It’s Racine who is turned on by taking blood; Anaia shudders, her morals compromised. In this story of inherited trauma, Anaia and Racine can be seen as halves of a shared consciousness: rage living with docility, agency living with passiveness. The perceived ugliness of Anaia has cast on her the sufferer’s nobility. (We join her in our minds with the beleaguered Celie, these women’s eyes beaming weakly at us.) At the end of the film, Man does meet his fate, a cleansing fire, which takes Racine, too. The last scene is of Anaia, who had been secretly pregnant, clutching her child happily in a sort of Eden, launching an alternative myth.