In a prologue set decades before the main events, a young girl watches from a blackberry bush as a dark-haired woman leads a ritual around a bonfire, reading from a black leather book and cutting her palm to bleed into the earth. A shadow appears at the clearing's edge, unseen by all except the woman. It slips through the circle, chilling each person it passes, then vanishes.
Twenty years after leaving Craw Valley, a small community in Appalachia, Lee Carnell drives from California with her two children: Meredith, a sharp-tongued teenager, and Cliff, a sensitive younger boy who perceives the world through colors and sometimes knows things he should not. Lee, whose birth name is Opaline Ford, renamed herself to shed her Appalachian identity when she left for college. She is fleeing a failed marriage after her husband Cooper Carnell's infidelity, and a prenuptial agreement leaves her with almost nothing. Her grandmother Belva Buck's cabin is the only place she can go.
At the cabin, Lee is greeted by Luann, a longtime family friend, and her uncle Billy, Belva's gentle son. She embraces Belva, overwhelmed by a sense of safety. That night, Lee recalls her childhood: the promise of a black book, the family's inherited spellbook for magical training, and her father Hank's death in a bridge collapse the next morning. After Hank's death, Lee's mother Redbud severed all contact with Belva and forbade Lee from learning the family's tradition of mountain magic. Later that night, Cliff screams that a shadowy figure crossed his room and opened the windows. Belva hangs rosemary and places protective charms.
Lee takes a substitute teaching position at the local high school, reconnecting with her former teacher Joseph Hall, who once mentored her through college applications, and encountering her cousin Dreama Conway, the daughter of Lee's late aunt Ruby Jo. Dreama is a polished businesswoman promoting Craw Valley's modernization. One evening, Otis, a man Lee shared a single intense kiss with in high school, arrives carrying his ailing father, who has multiple sclerosis. Belva performs a healing ritual, and Lee feels the old attraction return.
Days later, Lee's childhood friend Kimmie Ryder convinces Lee and Otis to attend a bonfire deep in the woods hosted by Kimmie's brother TJ, who carries an undercurrent of menace. Otis offers Lee moonshine stamped with a black flower symbol. After slipping into the trees with Otis, Lee glimpses a young girl, no older than 15, with Mr. Hall.
Lee tells Belva, who reveals a prior complaint against Hall was buried, and proposes a ritual to bind him. Lee refuses, but Belva proceeds. Meredith sneaks out to watch the gathering, feels the land's energy surge through her, and loses consciousness. The next morning, Lee finds Meredith missing. A search guided by Cliff's prophetic dreams leads to Meredith behind a boulder; she has gotten her first period. Nearby, they discover Mr. Hall's body with a flower-shaped brand burned into his thigh. The sheriff says off the record that the life appears to have been drained from the body. Lee resolves to investigate the black flower.
Tensions mount when Belva tries to give Meredith a black book for training and Lee forbids it. Meredith accuses Lee of keeping her from her culture and sneaks to TJ's property, where Redbud, whom she has never met, teaches her to channel the land's energy and promises secret lessons. When Lee goes to TJ's property, she recognizes his niece Missy as the girl from the bonfire and concludes TJ killed Hall in retaliation. Belva reveals the moonshine originates from dark flowers; her ex-husband became addicted and the Ryders took over production. Belva proposes a binding ritual against TJ; Lee participates but cannot access the land's power.
Meredith returns to TJ's property and finds Redbud and her classmate Tiffany Wang unconscious, a flower brand on Tiffany's thigh. When TJ's men grab Meredith, her attempts to use power fail, revealing that what Redbud taught her was illusory. Devastated, Meredith confronts Redbud and, in a burst of uncontrolled energy, knocks her unconscious. Soon after, Lee discovers TJ's dead body bearing the flower brand. At the police station, Belva is questioned aggressively and has a stroke.
At a pumpkin patch festival, Cliff senses the shadow, and Meredith vanishes from a corn maze. Lee goes to Redbud, who shares memories through touch. Lee learns the truth: The night before Hank died, Redbud discovered his affair with her own sister Ruby Jo and performed a spell to sever the relationship. A shadow appeared at the clearing's edge. The next morning, the bridge collapsed, killing both Hank and Ruby Jo. Redbud blamed Belva's magic and burned her black book. The shadow has tormented Redbud ever since, twisting her desires into horrific realities: Mr. Hall died because Redbud feared for Meredith, TJ died because she wanted to get clean, and Meredith was taken because Redbud wanted her for herself.
Lee reconstructs the spell using Belva's book, found under Meredith's cot. On the night of the ritual, she assembles a small group: Luann; Linda, a community ally; Billy; Redbud; Cliff; Otis; Kimmie; and Dreama. Lee surrenders to the land, and roots sprout from her feet as she is flooded with ancestral pain. A locket belonging to Pallie, Belva's grandmother, protects Lee when the shadow reaches for her. Redbud faces the creature, embraces it, and reabsorbs it into herself. She leads them to Meredith, who has been trapped in a cave behind an invisible barrier.
The family reunites, but that evening Lee finds Otis lying in a strawberry field with no pulse, the life drained from him. Lee discovers her own gift: the ability to enter others' minds through touch. A visitation from Pallie's spirit identifies Lee as an "observer," gifted with seeing into the depths of others rather than casting spells. Re-entering her mother's memories, Lee notices a crucial detail: The figure watching Redbud burn the black book was not young Lee but young Dreama.
Lee searches Dreama's property and finds a hidden underground room containing an apothecary, fresh black flowers, and Redbud's charred black book, retrieved from the fire 30 years ago. Dreama traps Lee inside. As Lee loses oxygen, her family mobilizes: Cliff senses her location, and Meredith and Redbud channel the land's energy to revive her.
The final confrontation takes place at the clearing, where four generations of Buck women face Dreama. She reveals that as a child, she overheard Ruby Jo and Hank planning to abandon her and her brother Earl, then watched Redbud's ritual and welcomed the shadow's vengeance against her mother. She used the stolen book to remake herself while undermining Belva's tradition. She killed Mr. Hall, killed TJ, and attacked Otis to sever Lee's ties to Craw Valley. Lee grabs Dreama's arm and enters her mind, facilitating a meeting between Dreama and Ruby Jo's spirit. Ruby Jo forgives her daughter and asks her to atone. Together, Lee and Dreama sever Dreama's connection to the land's power permanently.
In the aftermath, Belva and Redbud reconcile after decades of estrangement. Otis wakes from his coma. Lee and Redbud reconcile, and Lee decides to stay in Craw Valley to pursue a counseling degree. Meredith is recognized as a powerful conjurer, someone who can actively channel the land's power, and Cliff as the family's first seer, a member gifted with prophetic visions, in five generations. Lee attends recovery meetings with Redbud and remains sober. In an epilogue six months later, the community gathers for a spring celebration. Meredith leads the humming, and Lee takes her daughter's hand, finally becoming one of them.