Other Mommy Review: Rob Savage's Chilling Mixed Bag

Young Bela (a genuinely haunting Arabella Olivia Clark) is a lonely kid. Her real mom, Ursula, is... struggling. Let's call it that. When a strange, unsettlingly familiar figure appears in her home - a figure that looks exactly like her mother but with a smile that's all wrong and eyes that are just a little too dark - Bela doesn't run. She's drawn to it. This "Other Mommy" is everything her real mother isn't: attentive, playful, and always there. But as Bela's bond with this sinister doppelgänger deepens, the line between reality and a waking nightmare blurs, pulling her family into a terrifying, ever-darkening world where the ultimate question is: who's the real monster, and does it even matter?

Let's get the obvious out of the way: Jessica Chastain is having a blast. As the frazzled, imperfect Ursula, she's grounded and vulnerable. But as the Other Mommy, she's a live-wire, a child's drawing of a mother brought to terrifying, jerky life. Her performance is the film's beating, terrifying heart. It's a masterclass in duality, and she alone is almost worth the price of admission.

Director Rob Savage knows how to craft a scare. The film is dripping with atmosphere, and his use of sound - a distorted lullaby, the wet, snapping sound of something that shouldn't be moving - is expert-level. He understands that the most profound horror is intimate, and the idea of a child preferring a monster to their own parent is a deeply upsetting, fertile ground for a horror movie.

Unfortunately, the script by Nick Cuse and Michael Kennedy doesn't know what to do with that fertile ground. For the first half, Other Mommy is a slow-burn psychological thriller, and it's genuinely effective. You feel Bela's isolation, the tension in the house, the dread of something watching from the corner of your eye. But as the mystery unfolds, it buckles under the weight of its own mythology. It throws everything at the wall: sleep paralysis, doppelgängers, some vague, half-explained folkloric rules. The scares become louder and more frequent but less and less effective. By the final act, it devolves into a messy, CGI-heavy monster mash that feels like a completely different, far worse movie.

The supporting cast is also criminally underused. Jay Duplass as the bewildered dad is mostly just... there, while the usually excellent Dichen Lachman and Karen Allen are given little to do but react. It's as if the film is so enamored with its central, twisted mother-daughter dynamic that everyone else becomes set dressing.

Pros:

• Jessica Chastain's dual performance is a tour de force of creepy charisma and frazzled maternal guilt.
• Arabella Olivia Clark is a fantastic young lead, anchoring the film's emotional terror with a truly unsettling sincerity.
• Rob Savage's direction is stylish and atmospheric, delivering several genuinely skin-crawling moments in the first two acts.
• The core concept - a child's desperate need for a good parent creating a literal monster - is psychologically potent and deeply unnerving.

Cons:

• The third act is a total mess, abandoning psychological horror for generic, poorly-rendered creature-feature chaos.
• A convoluted and underwritten script introduces intriguing ideas only to drop them or explain them away clumsily.
• Wasted supporting cast, including talented actors like Dichen Lachman and Karen Allen, who have next to nothing to do.
• The scares become repetitive and over-reliant on loud noises as the film progresses, losing the subtle dread of its opening.

Other Mommy is a film with a split personality. For its first hour, it's an effective, slow-burn chiller with a phenomenal performance at its center. Then, it turns into a pumpkin. It's a frustrating experience because you can see the great movie buried underneath the messy one. If you're a die-hard Jessica Chastain fan or a horror completist, a matinee might satisfy your curiosity. But for everyone else, Other Mommy is a tantalizing look at a better film that just isn't there. The real horror here is wasted potential.