Note: This film's characters remain unnamed and are referred to solely by their descriptors.
The story opens dramatically with a woman amid crackling flames, her flesh rapidly charred, while screams echo hauntingly in the backdrop. Shortly after, we meet a man known as "Him," portrayed by Javier Bardem, who places a mysterious crystal object in his bedroom. Immediately, a transformation occurs as their home evolves from a desolate wreck into a beautifully renovated space. In this new environment, a young woman, referred to as "Mother" and played by Jennifer Lawrence, appears in his bed. Seeking comfort in his presence, she calls out for Him with a gentle, "Baby?" Yet, her call goes unanswered.
Curiosity leads Mother to explore their seemingly deserted house. As she steps onto the porch to seek out Him, he suddenly appears from behind and embraces her, surprising her momentarily. Him, a gifted poet struggling with writer's block due to the tragic loss of his first wife, reflects a sense of longing and introspection as they navigate their life together. Mother busies herself with her artistic endeavors, attempting to paint a room with vibrant colors. However, upon reaching the wall, she is confronted with a vision—a beating heart pulsating within the very structure of their home.
Their tranquility is soon disrupted by a knock at the door. Him invites a stranger, referred to as "Man" and played by Ed Harris, into their abode. Politeness reigns as Him engages with Man, but Mother feels an unsettling discomfort at his presence. Man mistakenly believes they operate a sort of bed-and-breakfast, and he expresses admiration for Him's literary work. Throughout this encounter, Mother feels overshadowed, voicing her own appreciation but sensing that her husband enjoys this newfound company more than hers. Amidst polite conversation, violent coughing fits frequently break Man's speech, prompting Him to express concern and care for him. Mother later bears witness to Man's struggle in the bathroom, where she discovers a shocking wound, a chunk of flesh missing from his ribs, hastily covered by Him.
As the sun rises on a new day, Mother inquires about Man's health. To her surprise, Man announces he feels wonderful before another knock disrupts the air. This time, it's Man's wife, referred to as "Woman" and portrayed by Michelle Pfeiffer. Him, ever accommodating, welcomes her into their home. While Him and Man embark on a hike, Mother finds herself alone with Woman, who probes her with uncomfortable questions about the possibility of motherhood and shows an unsettling interest in Him's office, which, she states, is off-limits without his permission. Upon their return, Man succumbs once more to his violent cough, leading to a revelation from Him: Man is dying, and he along with his wife have always admired Him's work, prompting their visit.
However, a fateful accident occurs when Man and Woman inadvertently shatter the crystal object, leading to devastation for Him, who frantically orders them out of his office. Grief-stricken and bloodied from gripping the shards, He acts as a protective husband as Mother, disturbed by their presence, demands they leave. Yet, Man and Woman disregard her request, retreating instead to another room, where they become intimate.
In a shocking twist, Man and Woman's sons, played by Domhnall Gleeson and Brian Gleeson, arrive, embroiled in a heated argument over their father's will. This feud escalates into violence, and chaos ensues when Oldest Son bludgeons Youngest Brother, leading Him to rush him to the hospital, accompanied by Man and Woman.
With the aftermath of this violence looming, Mother is left alone to confront a stubborn bloodstain that seeps from the floor, leading her to a disturbing discovery in the basement. As tensions rise inside the house, Him breaks the news to Mother that Youngest Brother has died, sparking a wake that gathers a host of unfamiliar faces. As these strangers flood into their once-peaceful home, Mother becomes increasingly distressed by their reckless behavior, fueling an argument with Him that ultimately culminates in a passionate reunion of their own.
Soon after, Mother joyously announces to Him that she suspects she is pregnant, igniting a spark of inspiration in Him to resume his writing. His work finally gains recognition, catching the attention of a prominent publication, "The Herald," represented by Kristen Wiig. As time passes, Mother reaches the final stages of her pregnancy, and the chaos amplifies as worshippers and fans swarm their home, breaking decorum and property amidst their fervent excitement.
The turmoil escalates as fans turn increasingly unruly, breaking possessions and tending to violent squabbles. Some guests are even bound and hooded while "The Herald" coldly executes brutal acts. It becomes tragically evident that these individuals are part of a cult, driven by fevered devotion.
As Mother's labor begins, Him leads her into the sanctuary of his office, where she gives birth to a baby boy. Triumphant yet protective, Mother refuses to let Him hold their child, imploring Him to expel the volatile fans. Exhaustion overtakes her, and she eventually dozes off while cradling her newborn. When she awakens, her heart sinks to discover her child is missing. In a horrifying act, Him showcases their son to the frenzied crowd, who handle the baby with gruesome care. Shortly after, tragedy strikes as the crowd matures into a vicious mob. Mother experiences the torturous moment when she realizes the ward had been shattered, fueling her desperate attempt to reach Him as they have taken their child from her.
Infuriatingly overwhelmed, she retaliates against the mob with fury and violence until she finds herself captured. Amidst the brutality, Him pleads for her safety. The pain crescendos to a tragic climax where Mother, seeking retribution, makes a damning choice—she sets their home ablaze. The reality of their chaotic life culminates in a violent explosion, consuming everything, while Him remains unharmed as he carries the scorched body of Mother from the inferno.
As she asks Him who he is, he replies with cryptic words, "I am I and you are home." When she presses further about his intentions, he desires nothing more than her love, promising that she can grant him this. In a horrifying twist, he reaches into her chest, extracting her heart, causing her body to disintegrate into ash—an echo of the desolation they endured.
Him, now clutching the heart, crushes it in his grasp, revealing yet another crystal object—a mirror of a prior fate. As he places this piece in the remnants of their now-totally destroyed home, a laugh escapes his lips, and in an eerily cyclical twist, the house begins to transform once again into something new. A young woman, a direct parallel to Mother, materializes in the bed and calls out for her husband, marking the start of a chillingly familiar cycle, leading her to call out, "Baby?"
