Other Mommy (2026) Plot Summary & Timeline

The film starts in the home of the Martin family. Father (or “daddo”) Russell (Jay Duplass) is playing with daughter Isabela/”Bela” (Arabella Olivia Clark) when mother Ursula (Jessica Chastain) comes to tell Bela to go to bed. After her parents leave, Bela whispers for her “Other Mommy” to come out so she can keep playing. She goes to the closet door a few times, where a golden flash of light shines in Bela’s face.

The next day, Ursula leaves for work while Russell takes a nap, and Bela prepares a project before starting her new school. She then appears to come back and starts cooking pasta for Bela, but she only puts in barely a splash of water, so the pasta starts burning. Ursula talks to Bela about she was once part of her heart while a single tear falls down her cheek. Bela realizes this is Other Mommy and starts to get frightened. Bela leaves the room until Russell sees the smoke coming from the kitchen. After he puts the pot in the sink to put out the fire, Russell gets freaked out and falls back into the glass door when he sees Other Mommy’s body twisted into a weird shape under the table. He and Bela run out as Other Mommy starts floating.

Police and medics arrive before the real Ursula gets home. While she does try to comfort Bela, the girl can sense some disconnect from her mom, and she also notices some strain in her parents’ marriage. After putting Bela to bed, the girl speaks to Other Mommy again, who tempts her by making the light glow in her closet again.

Ursula and Russell later host a party for the latter, while Bela is cared for upstairs by a babysitter named Calvin (Sean Kaufman). The couple’s friend Frank (Arian Moayed) shows up, though Bela tries to avoid him because she knows that he and Ursula have been having an affair. Bela tries to show Calvin that Other Mommy exists, and he briefly sees her crawling on the ceiling of her closet and gets spooked. After Calvin steps out, Other Mommy takes his form and tries to once again convince Bela to let her inside Bela’s heart. Bela punches the creature, whose Calvin disguise comes apart. Other Mommy causes Bela to fall through the ceiling and into the party. When Ursula tries to go after her daughter, Other Mommy makes herself visible to Ursula before Russell comes in.

The Martins stay with Frank in his high security home since they are too frightened to stay home. Frank locks the place down, but Other Mommy still finds her way to Bela. The girl asks her to make Frank “go away”. Other Mommy poses as Ursula to trick Frank before sticking her hand through his chin and out his mouth. She then tosses him around as Frank tries to shoot her. Ursula, Russell, and Bela witness the horror, and even though Bela kicks Frank his gun back to him, Other Mommy uses her powers to bend Frank’s body and then make him explode.

The family leaves Frank’s house and goes to a kids restaurant as they discuss heading to Russell’s mother’s house, even though Ursula is not keen on the idea since his mother is very into the supernatural. Bela goes off to play with another girl in the play pen, only to get lured into a trap by Other Mommy. She warps reality to make Bela sink into the ball pit and teleporting her to an ocean. Other Mommy tells Bela that Ursula never even wanted her, while Bela sees a mansion on a hill. Russell desperately tries to find Bela since he knows Other Mommy is there. The entity sends Bela (along with many of the ball pit balls) into the family’s car, where Ursula and Russell find her.

Seeing no other choice, the Martins head to the home of Grandma Ruth (Karen Allen) so that she can call her medium friends to come and try to expel Other Mommy from Bela’s life. Before they arrive, Ruth talks to Bela outside about knowing the right people to let into your heart, as well as the ones to keep out.

A team of ghost researchers/exorcists, led by Lois Anthony (Dichen Lachman), arrive at Ruth’s home. They determine that Other Mommy is a manipulative demon that wants to enter Bela’s heart because of how pure she is, and this would allow her to live in a real body. Removing her purity would cause Other Mommy to leave her alone. The team sets up salt around the house and begins a seance. Other Mommy reveals herself. Lois approaches her with fascination and touches her skin, getting some kind of glittery gold substance on her fingers. The substance then causes Lois to gruesomely melt before Other Mommy attacks and kills the rest of the team. The Martins flee once again.

With nowhere left to go, the Martins resolve to just return home. The family gathers weapons to use against her, but Other Mommy emerges and attacks. She drives them all into the basement, where she forces Ursula to tell Bela the truth about her life. Russell is not Bela’s biological father, as Ursula got pregnant before meeting him since she was married to someone else. Although Russell was eager to stick around and help, Ursula confesses that she was not ready to be a mother and initially didn’t want Bela because it felt like she was giving up her freedom, but she tells Bela she loves her. Bela is just left angry and heartbroken by the revelation, and she runs from her parents.

Other Mommy finds Bela locked in the bathroom, disguising herself as Bela. Bela almost allows Other Mommy to enter her heart for good, until she remembers Ruth’s words to her, since she said parents promising their kids, they will never get hurt is a lie, and Other Mommy promises Bela will never get hurt. Bela tears off Other Mommy’s skin and rejects her outright, banishing the demon for good. Bela runs back to Ursula and Russell.

Sometime later, the family is hanging up Christmas decorations. Bela looks over to Ursula, who looks as though she is still hiding feelings of unhappiness.