In the year 1918, amid the turmoil of the Spanish Flu pandemic and World War I, young Pearl, portrayed by Mia Goth, lives on a humble farm in Texas with her German immigrant parents. With her husband, Howard, serving in the war, Pearl's existence is dominated by her ailing father and her domineering mother, who insists Pearl prioritize caring for him and managing the family farm over her own aspirations.
Pearl's longing for adventure leads her to frequent the local cinema, where she is enchanted by the films she watches. She dreams of becoming a chorus girl, a desire that starkly contrasts her mother's expectations. To cope with her lonely life and family pressures, Pearl begins misusing the liquid morphine prescribed for her father.
At the cinema, she encounters a young projectionist, played by David Corenswet, who is drawn to her vibrant spirit. One evening, while cycling home, Pearl stops in a nearby cornfield and whimsically dances with a scarecrow, lost in her fantasies about the projectionist. After sneaking out to visit him, he shows her an illicit stag film titled A Free Ride and encourages Pearl to pursue her dreams abroad. However, she grapples with the guilt of leaving her family behind and candidly expresses a desire for their demise.
Pearl's sister-in-law, Mitsy (Emma Jenkins-Purro), shares news of an upcoming audition for dancers that Pearl views as her ticket to freedom. But when Pearl's mother finds a pamphlet she took from the cinema during dinner, a fierce clash erupts between them. Her mother harshly criticizes Pearl's ambitions, labeling her a "failure" and expressing a deep-seated fear of her daughter's growing darkness. In a moment of rage, Pearl accidentally ignites her mother’s dress, leaving her severely burned. In a state of shock, Pearl extinguishes the flames and moves her unconscious mother to the basement, leaving her father behind as she seeks solace in the projectionist's arms.
The following morning, as the projectionist drives Pearl home to prepare for the audition, he is unsettled by the sight of a maggot-ridden pig left on the porch. His discomfort grows as he realizes the inconsistencies in Pearl's stories. When he attempts to exit her life, Pearl's fury boils over, leading to a horrific act where she stabs him with a pitchfork and disposes of his body in a pond where an alligator, known to her as Theda, devours him.
Pearl checks on her mother, who is barely conscious, and in a moment of cruel decision-making, she sends her tumbling down the basement stairs. She dresses in her mother’s finery and, after preparing her father in a suit, she smothers him to death, rationalizing her actions as merciful.
Later, at the church audition, Pearl is greeted by a nervous Mitzy, who insists on going before her. Pearl performs passionately, only to be devastated when the talent scouts reject her for not fitting their image. Back home, Pearl confides in Mitzy about her frustrations with Howard, the farmhand who became her husband, and her desperation for love. She admits to her dark turn, reflecting on the animals she’s killed and the lives she’s taken, lamenting especially for her father. As their conversation unfolds, Pearl pressures Mitzy into revealing that she was selected for the dance troupe before coldly snuffing out Mitzy's life in a brutal act of violence.
With this horrifying turn of events, Pearl dismembers Mitzy, discarding her body to Theda. Seeking solace, she curls up beside her deceased mother, professing her love. Believing her mother was right about making the best of her life, Pearl resolves to create a welcoming home for Howard upon his return.
When Howard unexpectedly arrives the next day, he is met with the shocking sight of his wife’s grisly handiwork, as she welcomes him with a haunting mixture of joy and pain, forever altering the course of their lives.
