Other Mommy opens 9 October as reviews split on Chastain horror

Jessica Chastain plays mother and monster in Other Mommy, which opens in cinemas on 9 October 2026 amid sharply divided early reviews.

The horror film is directed by Rob Savage and adapted from the novel Incidents Around the House, according to Variety. Chastain stars as Ursula and her demonic double, the Other Mommy — a doppelganger, meaning an eerie lookalike who shares her face. Arabella Olivia Clark plays Bela, the teenager whose perspective drives the story, while Jay Duplass plays Russell, the father. The film runs 94 minutes, a compact length by modern studio standards.

Adaptation, in plain terms, means the screen story starts with a published book rather than an original script. That book supplies the central idea. The film then recasts it with actors, camera work and sound, a process that often condenses long interior passages into visual scenes.

The date itself tells a story. Universal moved the release from 8 May 2026 to 9 October 2026, The Hollywood Reporter reported last year. That shift placed it in October, the pre-Halloween corridor when distributors often schedule horror titles. Theatrical here means cinemas first, rather than a debut on a streaming service.

A short running time also shapes the cinema programme. Theatres can organise more showings in an evening with a 94-minute title than with a longer epic. That flexibility helps during a crowded autumn weekend when screens turn over quickly.

Reviews are split. Pre-release coverage characterised the response as mixed, according to Variety. Mixed, in this context, means some notices lean positive while others lean negative. It does not mean every outlet met in the middle.

Variety's own review was severe, calling it among the most limp and ineffectual films of the year and saying it misfires in every direction including its tone. Separately, The Hollywood Reporter reported that early reactions had branded it a hot mess and Chastain's worst movie in a long time. Those are the reviewers' characterisations, not a consensus, and they sit at the tougher end of that mixed picture.

For audiences, this means a brief cinema outing built around a familiar fear. No prior reading is required. A family home. A child who notices something wrong. A mother who is not quite herself. The hook is simple, and it fits the season.