Josh Malerman’s brother and his wife put their child to bed one night, and the child said goodnight to “Other Mommy.” That remark is the only true thing behind Other Mommy (2026). The film, in US theaters since October 9, 2026, is not based on a true story. It adapts Malerman’s 2024 novel Incidents Around the House, which is fiction. As for Other Mommy’s true form, the film never settles on one: she wears the mother’s face, then loses it in stages. That section is marked for spoilers below.

A goodnight in his brother’s house

Malerman, the author of Bird Box, told the story in a Q&A with The Nerd Daily:

“I’ve had the idea for some 13 years. My brother told me a story similar to the first chapter, about him and his wife putting their kid to bed for the night and the kid saying goodnight to ‘Other Mommy.’ … The little story stuck in a big way and finally, recently, I wrote the outline on the office wall. Then went for it.”

That is the record, and it is all of it. Malerman describes no haunting and names no other event from his own life that went into the book. The interview does not name the brother or the child, and neither do we.

The release added nothing. iHorror put it plainly on October 8, 2026: the film “is not based on a real haunting, but it does have a real-life starting point.” Savage’s interviews since then are about craft, not real events.

The novel

Del Rey published Incidents Around the House on June 25, 2024. Bela, who is eight, narrates it from Chaps, Michigan. An entity she calls Other Mommy comes out of her closet and keeps asking permission to enter her body. As her parents’ marriage comes apart, the entity grows more aggressive and starts to impersonate the people she loves.

Other Mommy’s true form (spoilers)

Stop here if you have not seen the film.

There is no single reveal. For long stretches Other Mommy is Ursula, played by Jessica Chastain: “the creature looks just like her mom,” in the words of Common Sense Media. The face is slightly off and the body moves wrong. AV Club’s Jacob Oller thought the film “is never better than when it simply allows its central monster to look like Jessica Chastain.”

Then the disguise breaks down. The kitchen scene from the trailer is an early crack, with Other Mommy folded under the table in what MovieWeb calls “a twisted form with many arms and legs.” Collider’s review sums up what follows: “Sometimes, Other Mommy looks like Jessica Chastain; other times, she looks like Jessica Chastain with eight legs. She also bleeds glitter, can become 100 feet tall…” Common Sense Media describes a body that “moves and twists unnaturally, levitates, and can suddenly have dozens of limbs.”

At the climax, in the plot summary on Wikipedia, her face starts to melt and she grows enormous, nearly crushing Bela with a gigantic hand. That is the closest thing to a true form the film offers: not a face underneath, but the face giving way.

How she was made

Savage, speaking to Phantasmag on October 9, 2026, rejected the practical-versus-digital question and added “a third point to that triangle, which is the performance.” Behind every effect, he said, is a human performer: Chastain or “one of our creature contortionists who were playing Other Mommy in her various forms.” He did not name them.

The cast lists on TMDB, TV Guide and Metacritic credit Hayley Spelman as “Other Mommy (Creature).” Which scenes are hers is not on the record. Avril Murphy, a stuntwoman from Clonakilty in West Cork, told the Irish Examiner in August 2026 that she was expected to double Chastain and took a creature role instead: “We had to contort our bodies and try to grab the actors while making these horrible noises.” TMDB’s crew list, which its users edit, names Jeremy Selenfriend as prosthetic designer.

Critics were harder on the late forms than on the early ones. AV Club objected to “a giant CGI monster that once looked like Jessica Chastain,” and That Hollywood Show found the creature “increasingly CGI-heavy.”

The book’s Other Mommy

The novel’s entity, as reviewers describe it, never passes as human. MovieWeb says she is described “as having avian features” and “an odor.” A staff review at Gibson’s Bookstore calls her “tall and thin with dark hair on the backs of her arms,” and says she sometimes has trouble forming her face, “so the eyes end up on the chin.” These are secondhand descriptions; we have not checked them against the text. The film went the other way and kept her a near-perfect copy of Chastain until it could not.

Ending and post-credits (spoilers)

In the film, a weakened Other Mommy offers Bela an end to pain if Bela lets it into her heart. Bela refuses, holding on to Grandma Ruth’s lesson that pain is part of life, and defeats it. Bela, Ursula and Russ survive. In the coda, months later, the family hangs Christmas lights, and Bela sees signs that her mother’s unhappiness is coming back.

The novel is bleaker. There, Other Mommy kills Grandma Ruth, impersonates her and draws Bela’s parents to their deaths, and Bela lets it in. MovieWeb notes that the film “ends on a more optimistic note, even if it leaves viewers to wonder whether Other Mommy is really gone.”

There is one scene at the very end of the credits. Other Mommy reappears, looks into the camera and shushes the audience, as MEAWW and FandomWire both report. There is no mid-credits scene.

The release, in numbers

Other Mommy opened at number one on the weekend of October 9–11, 2026. The studio estimate, reported by the AP’s Lindsey Bahr, was $27.5 million from 3,365 theaters, on a budget of about $19 million. The Numbers puts the actual opening at $27.8 million and, through October 14, the total at $35.2 million domestic and $58.8 million worldwide.

The verdicts were another matter: 16% on Rotten Tomatoes from 82 reviews, and a D+ from audiences polled by CinemaScore. Neither Universal nor Peacock has announced a streaming date.

Children who talk to someone who is not there

The goodnight is ordinary in one sense. In December 2004 the University of Washington reported a study in Developmental Psychology that followed 100 children aged six and seven. By age seven, 65 percent had had an imaginary companion. “Not all imaginary companions are friendly,” the researchers wrote. “A number were quite uncontrollable and some were a nuisance.”

Where it sits among ghost films

Savage’s first ghosts lived inside screens, in Host (2020) and Dashcam (2021), heirs to the fixed camera of Paranormal Activity and the line traced in how ghosts got on screen. Other Mommy is studio horror, a threat coming out of a closet rather than a laptop.

Its producer, James Wan, directed The Conjuring (2013), a film that did claim a true story, and whose real family and farmhouse tell a different one. Other Mommy claims nothing of the kind. On our list of ghost movies based on true stories it would sit beside Poltergeist (1982), the one film there that never claimed a real case. It is also on our Halloween watchlist.

What does not fit

The one real moment in all of this is the smallest. A child was put to bed and said goodnight to someone called Other Mommy, and a parent found it strange enough to tell a brother. Malerman kept it for about thirteen years, and the book became a film that opened at number one.

The book and the film each had to decide what Other Mommy looks like, and they decided differently. The film ends with her looking into the camera and asking for quiet. The child who said the name first never had to describe her, and nothing on the record says the child ever did.