In the burnt-out remains of a large house, Him, an acclaimed poet struggling with writer's block, places a crystal object on a pedestal in his study. The ruined house morphs into a lovely home in an edenic landscape. In bed, mother, the poet's wife and muse, awakens and wonders aloud where Him is. While renovating the house, she starts seeing things that unsettle her, including visualizing a beating heart within its walls.
One day, a stranger referred to as man turns up at the house, asking for a room and claiming to be a local doctor. Him readily agrees, and mother reluctantly follows suit. During his stay, man suffers coughing fits and mother observes an open wound in his side. Soon man's wife, woman, also arrives to stay. mother is increasingly frustrated with her guests, but Him begs her to let them stay, revealing to mother they are fans of his work and man is dying. However, when man and woman accidentally shatter the crystal object, which Him had forbidden them to touch, mother kicks them out and Him boards up his study.
Before man and woman can leave, their two sons arrive and fight over their father's will. The oldest son, who will be left with nothing, severely wounds the younger brother and flees. Him, man, and woman take the injured son for help. Alone in the house, mother follows a trail of blood to find a tank of heating oil hidden behind the basement walls.
Upon returning, Him informs mother the son has died. Dozens of people arrive at the house to honor the dead son. They behave in rude and presumptuous ways that irritate mother; she snaps when they break a sink, partially flooding the house. She orders everyone out and berates Him for allowing so many people inside while ignoring her needs. Their argument ends in passionate lovemaking.
The next morning, mother announces she is pregnant. The news elates Him and inspires him to finish his work. mother prepares for the arrival of their child and reads Him's beautiful new poem. Upon publication, it immediately sells out every copy. In celebration, mother prepares a big dinner, but a group of fans arrives at the house before they can eat. She asks Him to send them away, but he insists he has to be polite and show his appreciation, and tells her he will return soon. mother tries to lock the doors, but more fans arrive and enter the house, where many begin to use the toilet. They start stealing things as souvenirs and damaging the house, but Him is oblivious due to the adulation he is receiving. Hundreds of people fill the house and an increasingly disoriented mother watches it devolve into chaos. Military forces battle a cult of frenzied fans who tear rooms apart and engage in religious rituals. Amidst gunfire and explosions, the herald, the poet's publicist, organizes mass executions.
mother goes into labor and finds Him. He takes her to his study, which he reopens so she can give birth there. The havoc outside subsides. Him tells mother his fans want to see their newborn son; she refuses and holds her son tightly. When she falls asleep, however, Him takes their child outside to the crowd, which passes the baby around wildly until his neck is inadvertently snapped. mother wades into the crowd where she sees people eating her son's mutilated corpse. Furious, she calls them murderers and stabs them with a shard of glass. They turn on her, viciously beating and attempting to strangle her until Him intervenes. He implores mother to forgive them, but she escapes, makes her way to the basement oil tank, and punctures it with a pipe wrench. Despite her husband's pleas, she sets the oil alight; it explodes, destroying the crowd, the house, and the surrounding environment.
mother and Him survive; she is horrifically burned while Him is completely unscathed. He asks for her love and she agrees. He tears open her chest and removes her heart. As he crushes the heart with his hands, a new crystal object is revealed. He places it on its pedestal and, once again, the house is transformed from a burnt-out shell into a beautiful home. In bed, a new mother appears and wakes up, wondering aloud where Him is.
Mother! received polarizing, But mostly positive reviews from critics. On Rotten Tomatoes, The film has a score of 69% based on 366 reviews with an average score of 6.83/10.