Jessica Chastain’s ‘Other Mommy’ makes five major changes to horror book

Other Mommy, starring Jessica Chastain, makes several significant changes to Josh Malerman’s 2024 horror novel Incidents Around the House, including a gruesome death scene and a dramatically different ending.

The film follows Bela, played by Arabella Olivia Clark, a young girl who encounters a sinister entity that takes the appearance of her mother, Ursula, portrayed by Chastain. Although the adaptation retains the central threat, it changes key details to heighten the horror on screen.

One major difference is the demon’s appearance. In the film, the entity can convincingly imitate humans, although subtle signs reveal its supernatural nature. In Malerman’s novel, it has more distinctly unsettling features, including an avian appearance, unstable facial features and a foul smell that affects those nearby.

The séance sequence also differs considerably. In the film, Grandma Ruth, played by Karen Allen, organises a séance that summons the entity and ends with members of a ghost hunting group being killed. The book instead features fraudulent spiritualists who quickly admit they cannot help the family.

Another change involves a frightening encounter at a family entertainment restaurant. Bela follows what she believes is a new friend before the entity pulls her into an endless ball pit. The sequence develops into a surreal ordeal involving the sea and the family car. In the novel, the comparable incident takes place at a playground and ends with Bela suffering a serious fall.

The film also adds a particularly graphic death. Family friend Frank, played by Arian Moayed, becomes the target of the entity after Bela suggests her family might be better off without him. The creature kills him in a bloody scene. In the novel, Frank’s death is reported rather than shown in this manner.

The biggest change comes at the conclusion. The film ends with Bela resisting the entity, leaving her family together. The novel takes a far bleaker direction: the demon assumes Grandma Ruth’s appearance, leads Bela’s parents to their deaths and eventually takes control of Bela after she lets it into her heart.

These differences give the adaptation a distinct ending while preserving the story’s central psychological horror.