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A child seeing something frightening inside the house is already a familiar horror setup. However, Other Mommy gives that idea a deeply unsettling twist: What if the entity hiding in your home looked exactly like someone you trusted?

Based on Josh Malerman’s novel Incidents Around the House, Other Mommy follows eight-year-old Bela, played by Arabella Olivia Clark. Bela has been communicating with a mysterious presence that she calls “Other Mommy.” At first, her parents may be able to dismiss the encounters as part of a child’s imagination, but that explanation becomes harder to accept once the entity begins making itself known.

Other Mommy does not simply want to frighten Bela. She wants permission to enter her heart—and she is becoming increasingly impatient for an answer.

The first trailer offers a disturbing look at the entity haunting Bela’s family—and how Jessica Chastain transforms from a comforting mother into something deeply unnatural.

Jessica Chastain Becomes the Other Mommy

Jessica Chastain plays Bela’s mother, Ursula, as well as the disturbing figure copying her appearance. That gives the movie one of its strongest ideas: Bela and the audience may not always know which version of her mother they are seeing.

The trailer wastes little time turning Chastain’s familiar face into nightmare fuel. Other Mommy bends, crawls, smiles and moves in ways that immediately tell us something is terribly wrong. There is something especially creepy about an entity that looks almost human but cannot completely imitate how a person should behave.

Chastain previously explored supernatural horror in Mama and later appeared in It Chapter Two, but this role gives her the opportunity to portray both a frightened parent and the creature threatening the family. That contrast could make Other Mommy much more memorable than a traditional shadowy monster.

A Family Already Beginning to Crack

The supernatural threat is only one part of the story. Bela’s parents, Ursula and Russ, are already dealing with problems inside their marriage. Other Mommy appears to recognize those cracks and may use them to weaken the family further.

Jay Duplass plays Russ, while the supporting cast includes Dichen Lachman, Arian Moayed and Karen Allen. The story appears to remain closely connected to Bela’s perspective, placing the audience inside the fears of a child who understands that something is wrong even when the adults around her do not have the answers.

That approach could help Other Mommy stand apart from other haunted-house movies. This is not simply about a family discovering an evil presence. It is about a child being placed in the terrifying position of deciding whether she can trust the person standing in front of her.

Rob Savage Returns to Supernatural Horror

The movie is directed by Rob Savage, who previously directed Host and the 2023 adaptation of Stephen King’s The Boogeyman. Savage has shown that he understands how to create tension inside familiar spaces, and Other Mommy gives him an entire family home to transform into something threatening.

The movie is also produced by James Wan through Atomic Monster alongside Blumhouse Productions and Spin a Black Yarn. With that creative group involved, it is easy to understand why the trailer leans heavily into frightening imagery, sudden scares and a supernatural mystery.

Still, the most effective part of the trailer is not necessarily one particular jump scare. It is the uncomfortable feeling that Other Mommy could appear anywhere, imitate someone Bela loves and wait for the perfect moment to reveal herself.

Other Mommy Looks Like One of October’s Most Unsettling Releases

There are plenty of supernatural horror movies involving haunted houses and sinister entities, but Other Mommy has a strong central concept. Taking the person who is supposed to make a child feel safest and transforming her into the source of that fear is genuinely disturbing.

The body movements shown in the trailer are especially creepy. Other Mommy does not move like a typical person, and the unnatural physical performance helps sell the idea that this entity may be able to copy Ursula’s appearance without understanding how to exist inside a human body.

If the full movie can maintain that sense of uncertainty without relying entirely on jump scares, this could become one of the more memorable original horror releases of the Halloween season. Jessica Chastain playing both sides of the nightmare only makes the concept more interesting.

Other Mommy arrives exclusively in theaters on October 9, 2026.