Spoiler notice: Covers the official premise and trailer setup. The entity’s full nature, the family’s fate and the ending are not revealed.
Bela calls the presence in her home “Other Mommy.” The name sounds almost affectionate. What it describes is far more disturbing: something that resembles her mother and has begun forming a relationship with her.
Arabella Olivia Clark plays Bela, the young girl at the centre of Other Mommy. Jessica Chastain portrays her mother, Ursula, and the entity that copies her appearance. Jay Duplass plays Bela’s father, Russ. The family’s problem is painfully intimate. The danger wears the face of someone the child should be able to trust.
The trailer establishes a gap between Bela’s understanding and the adults’ alarm. She speaks of the presence with familiarity, while its encounters with the family expose something threatening. What sounds like an unusual companion becomes a problem her parents cannot explain away.
The idea is unsettling because a familiar face normally does so much work for us. It tells a child who is safe, who belongs in the house and whose reassurance to accept. An imitation makes those ordinary judgments unreliable. Looking like someone is no longer enough.
For Ursula, the premise creates a particularly cruel fear. She must try to protect her daughter from something using her own likeness to establish closeness. For Bela, the difficulty begins even earlier: understanding why a presence she recognises might be dangerous.
Director Rob Savage has described the film’s interest in identity and the different versions of themselves adults present. Read through that idea, the supernatural setup exaggerates a familiar childhood experience: children notice changes in adults long before they always understand them. Here, a change in the person standing nearby may have a terrifying explanation.
The film adapts Josh Malerman’s novel Incidents Around the House. Its family setting gives the horror a direct emotional stake. Home is supposed to be the place where Bela can ask her parents for reassurance. The entity makes that reassurance harder to trust.
The mystery begins with what Other Mommy wants, but the premise also raises a smaller, more immediate fear: how does a child decide whom to approach when comfort and danger can look the same?
Universal Pictures lists Other Mommy for U.S. theatrical release on October 9, 2026.
Sources: Universal Pictures’ official film page · PEOPLE’s trailer report · Entertainment Weekly’s interview with Rob Savage