Spoiler alert: This article reveals major plot details from “Other Mommy,” now playing in theaters.
“Other Mommy” makes several substantial departures from Josh Malerman’s 2024 novel “Incidents Around the House,” reshaping everything from its demon’s appearance to the fate of young Bela and her family.
The film follows Bela (Arabella Olivia Clark), a little girl befriended by a sinister entity that assumes the appearance of her mother, Ursula (Jessica Chastain). Despite less-than-enthusiastic reviews, the movie is contending to lead the weekend box office after a viral trailer frightened audiences nationwide.
While the novel explores Bela’s story in greater depth, the screen adaptation adds large-scale horror sequences, makes its supernatural threat a more convincing human mimic and trades the book’s exceptionally bleak conclusion for a comparatively hopeful resolution. Here are the five biggest changes.
Other Mommy looks far more human
On screen, the demon is generally skilled at copying human beings. Its disguise is not flawless: Other Mommy’s face sometimes droops, and the creature can appear to levitate slightly above the floor. For much of the movie, however, it remains a persuasive imitation of Ursula.
Malerman’s novel gives the entity more overtly disturbing qualities. The book’s version is more avian, with unstable facial features and a putrid odor. Its presence also carries an essence that makes some people cough. The film therefore places more emphasis on the uncertainty of seeing a familiar person who may not be what she appears to be.
The séance becomes a massacre
Grandma Ruth, played by Karen Allen, arranges one of the movie’s pivotal encounters with the supernatural: a séance involving a well-equipped but naive ghost-hunting team. The group succeeds in conjuring Other Mommy, only to be killed by the entity.
The comparable episode in the book unfolds much differently. There, the séance is conducted by fraudulent spiritualists. Rather than provoking a deadly confrontation, they quickly acknowledge that they cannot help and have become involved in something beyond their abilities.
A playground sequence turns into a ball-pit nightmare
The adaptation also relocates one of the story’s tense early incidents. In the novel, the sequence takes place at a playground and culminates in Bela suffering a major fall.
The movie transforms that material into an elaborate set piece at a restaurant resembling Chuck E. Cheese. Bela follows someone she believes is a new friend, but the figure is actually the demon. Other Mommy pulls her into a seemingly endless ball pit, prompting Ursula and Bela’s father, Russell (Jay Duplass), to dive in after her.
The sequence continues changing locations. Bela is transported to the sea and then to the family sedan, which has filled with ball-pit balls — and contains Other Mommy. The expanded scene gives the film a visually striking horror moment suited to its trailer.
Frank’s death becomes the movie’s goriest shock
One of the most dramatic additions involves Frank, played by Arian Moayed. After Other Mommy disrupts Russell and Ursula’s anniversary party, Frank invites the couple and Bela to seek safety at his mansion.
The refuge comes with its own strain. Frank is Russell’s friend, but he is also having a not-so-secret affair with Ursula, and Bela senses the family tension surrounding him.
While Bela is in the bathroom, Other Mommy approaches and manipulates her into agreeing that the family would be better off without Frank. The demon then murders him in front of Bela, culminating in an explosive and bloody destruction of his head.
Frank also dies in the novel, but the event is presented far less graphically. Ursula announces that he was discovered dead in a closet, sparing Bela from witnessing the killing directly.
The film reverses the book’s devastating ending
The largest change comes in the final outcome. Throughout the film, Other Mommy repeatedly asks Bela to let the entity into her heart. Bela ultimately refuses, defeating the demon and leaving herself, Russell and Ursula together as a family of three.
The resolution is not entirely free of unease. The movie retains a suggestion that Bela will continue to feel some discomfort around her mother, even after Other Mommy is defeated.
The book denies Bela and her parents that survival. In its ending, Bela discovers that the demon has killed Grandma Ruth and styled itself after her. Disguised as Ruth, the entity draws Russell and Ursula to their deaths.
Left completely alone, Bela finally agrees to let Other Mommy into her heart. That decision allows the demon to take over Bela’s body while Bela is consigned to the purgatory from which the entity came.
ShowBiz Take
These changes do more than condense a novel for the screen. They alter the story’s balance of horror. The movie heightens immediate spectacle through the ghost-hunter deaths, the shifting ball-pit sequence and Frank’s graphic murder, while making the demon itself less visibly monstrous for much of the runtime.
Most significantly, the adaptation gives Bela the power to reject Other Mommy and preserve her family. The novel ends with isolation, possession and the deaths of Russell and Ursula; the film keeps the central trio alive, even as it leaves a trace of uncertainty in Bela’s relationship with her mother. That sharp contrast makes the two versions fundamentally different experiences, despite sharing the same child, demon and dangerous invitation.